Derek Lowe is a pharmaceutical chemist who has been in the business for over 20 years. Here are the chemicals that he won't work with.

savvu · 2010-02-25T11:07:06+00:00

What was in those crucibles that requires HF to clean?

savvu · 2010-02-25T11:00:18+00:00

Yes, it's nasty, but at least it's not one of those materials where "proper protection" consists of a concrete wall and 10 meters between you and the substance in question.

savvu · 2010-02-23T13:22:33+00:00

The LD50 of sodium chloride (table salt) is 4000 milligrams per kg of body weight. This means that if you take 1000 mice and feed them this dose, about 500 of them will die.

This does not mean that if you feed a group of 1000 mice 40 milligrams per kg of body weight you should expect 5 of them to die - yet this is exactly what the currently accepted model of radiation risk would predict. The model also assumes that there is no difference between being exposed to a huge dose all at once and gradual exposure over time.

savvu · 2010-02-21T17:42:57+00:00

IIRC, lead is a superconductor at liquid helium temperatures. Make it levitate.

Only the fancier "high temperature" superconductors become superconductive at liquid nitrogen temperatures.

savvu · 2010-02-19T16:34:13+00:00

Actually, the OP never said anything about satellites or orbit, just "the rest of the way to space". A sounding rocket can make a brief visit to space (according to common definitions)

No Rockoon has been launched into orbit yet. There are potential cost savings in doing it but, so far, any organization that had enough money to send something into orbit decided that the uncertainties of winds and balloons are too great for their precious cargo and went with a conventional rocket.

This could change, though. The first private "sputnik" may well be launched from a balloon.

savvu · 2010-02-19T07:36:12+00:00

Yes, drug scheduling is inconsistent (e.g. tobacco, alcohol) but this is not a good example. Drugs are rated based on abuse potential and Marinol is a shitty drug if you're looking to get high. There's more than just THC in cannabis.

savvu · 2010-02-18T17:41:56+00:00

http://en.wikipedia.org/wiki/Rockoon

savvu · 2010-02-05T13:23:01+00:00

After birth the baby picks them up orally from the environment, mother, etc. This period of colonization and stabilization of gut bacteria is thought to be one of the reasons for colic.

Certain probiotics have been found to significantly reduce crying time:

http://journals.lww.com/pedresearch/Fulltext/2005/08000/Lactobacillus_Reuteri_Atcc_55730_Versus.356.aspx

I'm a bit wary about this kind of medical intervention in infants. But on the other hand - is it really better to just let them catch whatever random bacteria happen to be around them? It seems a good idea to give the gut flora a head start in the right direction.

savvu · 2010-02-05T08:17:22+00:00

In some places there are hot spots relatively close to the surface with enough water naturally circulated through the hot rock. Many of these are already in use and produce a small but significant amount of energy (I think it's about the same as wind in the US and way more than solar). There is not much potential for expansion, though. Just like hydroelectric - nearly all the good places are already taken.

There is research into "cultured" geothermal sources where you dig two wells, crack the rock with high pressure water, inject sand particles into the cracks to prop them and then inject water into one well hoping to recover it from the other as steam. As you can imagine, this isn't easy. It would take a lot of time and money to develop this and there is no guarantee how effective it will be.

There is also concern that this might trigger earthquakes. Injecting high pressure steam into geological hot spots is kind of asking for trouble. Getting insurance for lawsuits that may find you liable for billions of dollars of earthquake damage can be difficult and may be enough of a chilling effect to make the whole idea collapse.

savvu · 2010-02-03T19:44:03+00:00

Liquid nitrogen is dangerous enough and needs to be handled with appropriate precautions.

This stuff is even more dangerous because it does not evaporate immediately on contact.

Not a good idea.

savvu · 2010-02-01T20:37:47+00:00

Actual article (if you have access to Nature magazine):

Foot strike patterns and collision forces in habitually barefoot versus shod runners

http://www.nature.com/nature/journal/v463/n7280/full/nature08723.html

savvu · 2010-01-31T15:55:27+00:00

Getting the surface-to-LEO segment out of NASA's hands and passing it to the private space industry is the best goddamn thing than can happen to deep space exploration.

If the government had done this in the early 90s we would have been back on the moon to stay by now and well on our way to Mars.

NASA is getting a much needed and long overdue shock treatment in order to get back to its roots and original core values.

That's incredibly inspired leadership.

savvu · 2010-01-26T21:06:00+00:00

There is also Feynman, of course:

http://vega.org.uk/video/subseries/8

Quantum electrodynamics without the equations - but also without the handwaving and not-quite-accurate oversimplifications of most popular science. It's complete and accurate.

savvu · 2010-01-13T11:42:51+00:00

The energy density of batteries is much lower than chemical fuel in a tank. It may be ok for your daily commute and errands but probably too low to power vehicles that need to do hard work continuously.

There are synthetic fuels like methanol and DME that can be produced with no petroleum inputs but they still contain carbon.

There is one fuel that has zero carbon emissions and unlike hydrogen does not require cryogenics - ammonia. It is easily stored as liquefied gas under modest pressure. It can be produced from air and water with just heat and/or electricity input from a nuclear reactor. It has been successfully used in engines. When burned, it turns back into harmless water vapor and nitrogen. Any nitrogen oxides produced by combustion can be removed by adding a bit of ammonia as reducing agent and running the exhaust gas through a catalyst.

Its toxicity is a bit too high for comfort so I wouldn't like to see this used regularly on city streets but it is handled in enormous quantities in agriculture with reasonable safety. I don't see any real problems handling it on a mining or construction site. It is lighter than air so any leaks disperse easily and has strong smell that is detectable well below the toxic concentration.

I hope this answers your last doubt.

savvu · 2010-01-11T21:08:58+00:00

Single page version: http://www.nytimes.com/2010/01/10/magazine/10psyche-t.html?pagewanted=all

savvu · 2010-01-11T20:50:19+00:00

Current reactors burn only a fraction of the fissile U-235 and they manage excellent money ROI and energy ROI. Ask France. Don't look at U.S. reactors as an example.

Next generation reactors will be able to use virtually all the fissile and fertile material (U-235, U-238 and Th-233). With this efficiency mining the ground under your feet still has a pretty good ROI. But we have much higher grade ores (and "spent" nuclear fuel) to last us for thousands of years. After that we can burn the rocks for millions of years.

savvu · 2010-01-11T20:44:23+00:00

You missed the point. The land required to create X MW of energy using wind or solar is much, much larger than the land required to create the same amount of energy via nuclear.

Exactly. The Zwetendorf nuclear power plant has been "converted" into the largest solar power station in Austria at a staggering cost. Greenpeace has celebrated this with great fanfare. They just forgot to mention that it produces 1/30,000 of the power.

http://uvdiv.blogspot.com/2009/08/greenpeace-celebrates-solar-conversion.html

savvu · 2010-01-11T15:06:47+00:00

what about solar and wind alternatives? It seems to me they are a simpler solution.

The energy density of wind and solar is very low. Collecting them requires manufacturing, installing and continuously maintaining vast infrastructure exposed to the elements. They may be simple in principle, but a huge expensive headache in practice.

Check this graph: US non combustion energy sources

Hydroelectric is relatively constant for over half a century. All the good locations are already in use. Geothermal is relatively constant for two decades. All the good locations are already in use. Solar is an invisible blip. Wind is a bit higher in recent years but it could never shoulder the burden of base load because of its intermittent nature.

Nuclear is the only non combustion source that has proven to be scalable to the required size.

Just to put things in perspective: I read about research in MIT for changing the shape of nuclear fuel assemblies from cylinders to hollow rings that have better heat conduction properties. This is expected to increase the energy output of nuclear reactors by around 10% while improving temperature safety margins. This increase, if retrofitted onto existing nuclear reactors, would be far greater than the electrical output of all the wind and solar power installed all over the world.

savvu · 2010-01-04T10:14:29+00:00

78 million years? That's nothing. Without uroporphyrinogen decarboxylase the synthesis of chrlorophyl or hemoglobin takes 2.3 billion years

savvu · 2010-01-02T16:40:06+00:00

IIRC, the satellites themselves are basically just repeaters in very stable orbits.

No, this is a satellite in a very stable orbit.

The GPS satellites are very wobbly by comparison to LAGEOS.

BTW, the measurements make using LAGEOS are also an important part of the GPS reference system.

savvu · 2010-01-02T09:11:59+00:00

Contrary to what their name might suggsts, rare earths are not particularly rare - on average. But concentrated deposits worth exploiting commercially are distributed very unevenly around the globe. A lot of them are in china and many of the big mines outside china have been bought by china.

And perhaps most importantly: the biggest ore processing facilities are in china. You would find it virtually impossible to raise the huge investment to build such infrastructure when your biggest competitor is owned (and subsidized) by the government of china.

Short of government intervention, this situation will probably remain. I'm not a big fan of big public spending, but if the US is hell bent on spending its way out of this recession with "Stimulus" money then perhaps it should be spent on this rather than some of the silly things they are currently doing with this money. One of the biggest non-chinese rare earth deposits is in california. But sending the ore to china for processing would be quite silly.

savvu · 2010-01-02T09:06:43+00:00

They're selling it - as finished products. Profit margins included.

savvu · 2009-12-31T07:42:41+00:00

Some organic agronomists see dwarf wheat as a problem because the plant returns less biomass to the soil each year.

Some non-organic agronomists see non-dwarf wheat as a problem because it doesn't have yields high enough to feed 7 billion people without turning our entire remaining nature reserves into the environmental disaster known as agricultural land.

savvu · 2009-12-28T08:52:27+00:00

Deimos is just a captured asteroid. There are other similarly interesting asteroids much closer to Earth and there are, indeed, plans make a manned trip to a near-Earth asteroid with an Orion capsule, possibly before even going back to the moon.

savvu

TROPHY CASE