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Check out the movies. Now THAT'S sexy!

Some more Titanium info, but this site is just way sexy. Check out the Flash Periodic Table on it.

Remember this post? "The Periodic Table of Comic Book Elements" from 2 days ago. The main site seems to have been fatally slashdotted, but here's Titanium on a mirror. Not so sexy, but timely. ;-)

Gold-plated iridium tablets?! OK, clearly you're just clueless and way out of your depth. Get back someday when you know what the big words mean.

What exactly is the problem with the original poster's statement? Iridium seems to be a valid candidate for a long-lived data storage substrate. Were you suggesting that the gold-plating would be redundant because iridium already has excellent corrosion resistance? Or something else?

Quote: "Barring a new invention, which is always possible, "It should take us to the end of silicon...as we know it today," he [Chuck Gwyn, program director for EUV at the Lawrence Livermore National Laboratory in Livermore, Calif.] said."

The limit for Silicon is hit when the paths "lithogrified" onto the wafers are less than a certain width, by this time measured in number of atoms. The distance between silicon atoms in a wafer is (again AFAIK) 0.235 nm, so today's 0.13-micron processes (130 nm) mean average path widths of ~550 atoms ... and I assume it will take a couple of dozen, at least, to make sure the yield doesn't drop through the floor.
So - this is not about anything other than silicon, just the limits of this particular semiconductor.

What else is there? Gallium Arsenide, AFAIK. But that's another story.

What the previous poster meant was, that
1 molocule Hydrogen (H2) + 2 of Oxygen (O2) gives 2 of water (H2O).
If Slashdot accepted PRE, SUPER, and SUB tags, this would be a lot clearer.
You are right, it takes a lot of energy to make Hydrogen, but according to Web Elements the normal approch to making Hydrogen is stream + ( carbon or methene), electrolsys of sulphuric acid (SO4+ goes through a complex system, and releases Oxygen, but is far more conductive that water) is too expensive, but it might be different if you want an oxygen supply as well. The reactions above produce carbon dioxide, so unless its aneroibic methene, Hydrogen rockets will still produce excess CO2.

Anyway, for space launchs, the rocket must either be self powered, or doing atleast the escape velocity when it leaves the end of the launch-rails, which, for the Earth, is 11km/sec, well above the speed of sound, so unless you lauch from the top of a mountain, there will be too much atmospheric drag for non-self powered lauches.
To determine the escape velocity use this formulae
sqrt(2 * Gc * M / r) (from Astronomy 120)
Where Gc is 6.6725e-11 kg-1m-1s-4
M is planent's mass 5.9 72e24 kg for Earth
r is distance of launch from planet's centre (6.378e6 m)

Elemental Gallium also has the property of expanding when it freezes. Gallium metal is interesting stuff - you can melt it in the palm of your hand, and it wets glass and porcelain.

Except that, err, the web didn't exist then, let alone a useful search engine...

To be fair, my initial research did run across its "interesting" magnetic properties, and I spent at least fifteen seconds commenting upon them in my oral report. I think the next person went on to talk about iron, or sodium, or some other glamorous element.

Fortunately holmium has found another practical application in recent years. In the words of Pomona's online periodic table "few uses were known for holmium until recently, with the development of surgical lasers using holmium."

There you have it. Using Google.

I apologize profusely for my libelous comments thrown so recklessly upon the respected name of this most venerable and miraculous element.

So by God, if there's holmium on the moon, we should feel obligated to liberate it from its lunar prison irrespective of any cost! Away to the moon we go; we haven't a day to spare!

Hydrogen nucleus - 1 proton

Helium - 2 protons, 2 neutrons

We don't care about the electons since their mass is 1/1836 of an amu.

As far as the mass of a volume of a gas goes, the ideal gas law states that

PV = nRT

Where P=pressure, V=Volume, n=quantity (usually in moles), R=ideal gas constant, and T=absolute temperature

Molecular/molar mass or size does not play a role in this relationship. BTW, here's some information on hydrogen for people who are interested, although the site does imply that hydrogen played a role in the hindenberg disaster, which has apparently been stripped of the crown as the cause of the fire/explosion, losing out to the champeen, solid rocket fuel. woo.

That's a very interesting question. According to Webelements Ununhexium (element 116) only existed as a shortlived decay product of 118.

The WebElements page for 118 has information about, and a link to, the retraction (the 116 page doens't) But reading the retraction, though it mentions 116, doesn't retract any claim regarding the existence of 116. So its possible that when the krypton collided with the Lead, an alpha particle was thrown off in the creation of Ununhexium, rather than during the decay of Ununoctium.

However, IANANP (I am not a nuclear physicist), so what do I know?

It's a great idea (and ameliorates the excess cow problem as well). Unfortunately, in some studies we performed for BARPA (Bovine Advanced Research Projects Agency) a while back we encountered some serious technical problems:

1. Coefficient of Drag: The average cow's drag coefficient (even in the most aerodynamically efficient "ass-backwards" posture) is approximately 0.6, as compared to 0.02 for a well-designed streamlined warhead. Since terminal velocity scales with square root of drag coefficient in the high-velocity limit, and kinetic kill energy scales with velocity squared, this yields a 30-fold reduction in energy on target.
2. Density: The density of a typical Hereford is 1.1 grams per cubic centimeter. In contrast, the density of depleted uranium is closer to 19 grams per cubic centimeter. The 19-fold reduction in gravitation force then reduces terminal velocity by 19 times, with a consequent 19-fold reduction in kinetic energy on-target (assuming drag force proportional to velocity squared).
3. Ablation: The real killer here is premature ablation of the bovine carapace. Reentry from 400,000 feet can raise the temperature of the cow's exterior surfaces to 3000 K. First off, the water evaporates, then the fats burn off, leaving a dessicated cinder. Even worse the density of the resulting cow cinder is greatly reduced, reducing terminal velocity further. The only advantage here is the nice sizzling barbeque smell that permeates the stratosphere on reentry.

That said, of course we recommended further study.

I'm looking at my sigaret lighter now. It's one of those see through models. It seems as though there is some fluid in there. If I let some of that fluid escape, it's suddenly not a fluid! Huh? But it is at room temperature! Huh? And it is methane! What? I just read this is impossible.

What exactly is ruthenium?

Make sure to keep all potassium chlorate away from these drives!! "The metal is not attacked by hot or cold acids or aqua regia, but when potassium chlorate is added to the solution, it oxidises explosively. "

If anyone is interested, I just looked up the critical point for nitrogen at webelements.com. It's 126.2K [or -146.9 C (-232.4 F)]. Regardless of the pressure, it is not possible to liquify nitrogen (or keep it liquid) above this temperature.

This has been one of those Real Soon Now (tm) projects for years, for a simple reason - assuming your solar cells are made of silicon or something of similar density, the mass of an SPS (solar power satellite) big enough to generate useful amounts of power is prohibitive.

Here's my calculations:
Assuming a solar cell 1m to a side and 1mm thick, we get: 0.001m^3/cell * 2330 kg/m^3 (the density of silicon from Webelements ) = 2.33 kg per cell.

The solar irradiance at Earth's orbit is 1367.6 W/m^2 (from NASA National Space Science Data Center ). We currently have solar cells that can convert solar energy to electrical energy at about 30% efficiency in the labs. So, we'll assume that these can be made in bulk sometime in the near future. That yields 1367.6 * 0.3 = 410.28 W/m^2.

That seems like a lot, but consider - it four 100 watt light bulbs, or your computer (no monitor), if you have a system like mine. Lets say we aim for a generating capacity nearer to your average nuclear plant - 2 megawatts. Then we need 2,000,000 / 410.28 = 4,875 panels. At 2.33 kg each that's 11.4 metric tonnes. Not a huge amount, but then you have to add about that much in support structures, repair equipment, and the microwave emmitter, of course.

You will note that I have ignored losses in transmission, etc after the power is converted from solar to electrical. That is because these conversions are all very efficient, compared to the solar/electrical conversion, so they don't change any mass calculations by that much.

So how many SPS units would we need to power the world? From the CIA World FactBook , the US in 1998 used 3.365 trillion kWh, equivalent to a continous 384 million kW. We would therefore need about 200 thousand of the 2 megawatt stations considered above, for the US alone. If we wanted to be generous and extend this technology to the rest of the globe, we need over 2 million stations of this size.

Now, this is clearly not economical, not with launch costs in the neighborhood of $500/kg for the Shuttle (some dumb boosters can haul more for only $100/kg), but there is still hope. John S. Lewis, in his book Mining The Sky shows that building SPS units is economical, if you don't have to launch the mass of the solar cells. Instead, you bootstrap - launch a processing facility to a target Near Earth Object, set down and start making solar cells. The facility would have to be unmanned, but it would in a few years time produce enough cells to build a SPS.

One thing's for sure: You sure won't see any of this from NASA. They'd like it if you gave them the trillions of dollars it would take to build one of these, so they could fail miserably and call the whole idea impossible.

---------------

Thanks. Some questions tho, if you or anyone else knows answers to them too:

First, the reports I read in the media indicated there was a significant amount of radioactive iodine released, how did the thyroid dose compare with the astatine?

Since I find astatine in the Webelements periodic table just under iodine and so it presumably is concentrated in the thyroid because it is mistaken for iodine, does a dose of (ordinary) iodine protect against it like it does iodine radioisotopes?

Last, since astatine isotopes have a max half life of a few hours compared to I131, how the hell do the amounts accumulate in reactors in the amounts that were measured as released, or last long enough to be ingested?

Thanks. Some questions tho, if you or anyone else knows answers to them too:

First, the reports I read in the media indicated there was a significant amount of radioactive iodine released, how did the thyroid dose compare with the astatine?

Since I find astatine in the Webelements periodic table just under iodine and so it presumably is concentrated in the thyroid because it is mistaken for iodine, does a dose of (ordinary) iodine protect against it like it does iodine radioisotopes?

Last, since astatine isotopes have a max half life of a few hours compared to I131, how the hell do the amounts accumulate in reactors in the amounts that were measured as released, or last long enough to be ingested?

-Daniel

"While hydrogen is the lightest element, it has some tricky characteristics. It only becomes liquid at dramatically low temperatures -- -423 degrees Fahrenheit (-253 degrees Celsius). To keep the fuel that cold, fuel tanks in the BMW cars are made of 70 layers of fiberglass and aluminum."

• At low temperatures, many electronics have much better performance. Thermal noise is reduced, transistors switch faster, and laser diodes are brighter. The backyard astronomer could make near-zero K amplifiers or CCD cameras for radio or infra-red astronomy, and the computer hobbyist could overclock his computer to unheard of levels.
• A lot of materials superconduct at that temperature.
• Liquid Hydrogen is an ideal fuel for a lot of purposes. It is powerful, and it can be used to cool the engine too. (Model planes or rockets, gas turbines, etc... )
• If you have liquid Hydrogen, you can use it to make liquid air and then by simple distillation, liquid Nitrogen (77.3K) and Oxygen(90.2K)!

"While hydrogen is the lightest element, it has some tricky characteristics. It only becomes liquid at dramatically low temperatures -- -423 degrees Fahrenheit (-253 degrees Celsius). To keep the fuel that cold, fuel tanks in the BMW cars are made of 70 layers of fiberglass and aluminum."

• At low temperatures, many electronics have much better performance. Thermal noise is reduced, transistors switch faster, and laser diodes are brighter. The backyard astronomer could make near-zero K amplifiers or CCD cameras for radio or infra-red astronomy, and the computer hobbyist could overclock his computer to unheard of levels.
• A lot of materials superconduct at that temperature.
• Liquid Hydrogen is an ideal fuel for a lot of purposes. It is powerful, and it can be used to cool the engine too. (Model planes or rockets, gas turbines, etc... )
• If you have liquid Hydrogen, you can use it to make liquid air and then by simple distillation, liquid Nitrogen (77.3K) and Oxygen(90.2K)!

"While hydrogen is the lightest element, it has some tricky characteristics. It only becomes liquid at dramatically low temperatures -- -423 degrees Fahrenheit (-253 degrees Celsius). To keep the fuel that cold, fuel tanks in the BMW cars are made of 70 layers of fiberglass and aluminum."

• At low temperatures, many electronics have much better performance. Thermal noise is reduced, transistors switch faster, and laser diodes are brighter. The backyard astronomer could make near-zero K amplifiers or CCD cameras for radio or infra-red astronomy, and the computer hobbyist could overclock his computer to unheard of levels.
• A lot of materials superconduct at that temperature.
• Liquid Hydrogen is an ideal fuel for a lot of purposes. It is powerful, and it can be used to cool the engine too. (Model planes or rockets, gas turbines, etc... )
• If you have liquid Hydrogen, you can use it to make liquid air and then by simple distillation, liquid Nitrogen (77.3K) and Oxygen(90.2K)!

The earth is big and heavy, so all the really valuable heavy metals like gold, platinum, etc. tend to sink deep into the Earth so they end up being relatively rare on the crust. Most asteroids, however, are fairly homogeneous collections of the heavy material that made our solar system, so they are chock full of the valuable heavy metals. For instance in the case of Gold, meteorites have concentrations about 50 times greater than in the Earth's crust. I got this information from Webelements under the geology link for gold.

Just ask Jeeves ... In 1807, Davy proposed the name alumium for the metal, undiscovered at that time, and later agreed to change it to aluminum. Shortly thereafter, the name aluminium was adopted by IUPAC to conform with the "ium" ending of most elements. Aluminium is the IUPAC spelling and therefore the international standard. Aluminium was also the accepted spelling in the U.S.A. until 1925, at which time the American Chemical Society decided to revert back to aluminum, and to this day Americans still refer to aluminium as "aluminum". here is the whole page ...

Uh, no.

Weapons grade uranium is 90% U235. The rest is U238 (plus some other junk).

The uranium used in reactors is also U235.

Naturally occuring uraniu m is 0.72% U235.

Naturally occuring uranium is slightly enriched, to 3% U235, for use in reactors.

And, actually, there are multiple ways of seperating isotopes. Centrifuging uranium hexaflouride is just the cheapest and easist way, requireing ten passes to get weapons grade. Previously, magnetic deflection of ions (like in a mass spectrometer) was used.

Ok, to return to my point, I should have said the most difficult part in getting fuel grade uranium to explode, is the construction.

The reason weapons grade uranim is used is because it's a lot easier to make explode, in a controlled manner. And it gets you big bangs.

Fuel grade uranium will not get you a much bigger bang than, say, 13 kiltons, assuming your careful about how you build it.

That is a mere fire cracker compared with todays 100 megaton bombs. At one 100000th of that power, it's the same size as the Hiroshima bomb.

If you were ever going to build one from fuel grade uranium, it would be a terror weapon. Even if all it did was blow up a block, that wuold do.

[Aside: Fuel grade uraium can be made into a bomb: the chain reaction co-efficent of a nuclear reactor is 1 (by definition). This is controled by control rods, that allow the maximum chain reaction co-efficent to be reduced (but not enchanced). Thus the natural peak chain reaction co-efficent of the fuel must exceed 1.]

Alternativly, you could build an FBR to produce plutonium, but that's getting off the point.

The "Coal" itself is not radioactive. Its the (radioactive) halogen gas Radon that is set free when Coal is cracked. As a coal plant needs huge amount of coal to run (compared to the relative small amount of Uranium needed for nuclear plant), more Radon is set free by a properly run coal plant than by a properly run nuclear plant.

Sadly, reviewing the chemistry database, I see this reaction for Calcium Carbonate (limestone) and HCl (hydrochloric acid):
CaCO3 + 2HCl -> CaCl2 + H2O + CO2

So, no resulting hydrogen, just water and CO2. Completely impossible premise unless the dragon's digestive track had a good way of taking care of the CO3 (carbonate) part of Calcium Carbonate.

Well, if you really want good thermal contact, the best thing to use is indium, a soft metal. To make it work ideally, you'd remove the paint (or anodization, though Al2O3 has pretty good thermal conductivity) and use pressure. The indium fills in all the voids and eliminates a great deal of the thermal resistivity of the interface, which is probably as great as that of the thermal goo.

You might want to rethink that brick house. You will actually get more of a dose from a brick house than a wood house, since the bricks themselves release radiation.

But the wood emits radiation as well. Every living or once-living thing (wood included) contains a fair amount of carbon. No, most of the naturally-occurring isotopes of carbon aren't radioactive, but carbon-14 is. How do you think they are able to do carbon dating? Carbon-14 is a naturally occurring radioisotope of carbon with a half-life of 5715 years. Therefore, all living things are slightly radioactive. Therefore, wood is radioactive. Therefore, YOU are radioactive.


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