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May 31

Nanocrystalline silicon?

Why is it thus called, if the grain sizes are not on the nanon scale, but rather on the micron scale? Plasmic Physics (talk) 00:08, 31 May 2013 (UTC)[reply]

Who calls it that? I've never heard of it. I've heard of polycrystalline silicon. In science, it's nearly a certainty: if something exists, somebody has called a version of it nano-something. Nimur (talk) 00:32, 31 May 2013 (UTC)[reply]

Because it has only been known how to make and study nanocrystalline substances in recent years, from when the semiconductor industry developed nanocrystaline silicon - so a term for such substances was not needed. The term microcrystaline had already been in use for very many decades, and simply means a substance where the crystals are too small to see with the naked eye, requiring an optical microscope to be used. Nanocrystals are too small to be seen with a traditional optical microscope, although in theory an optical microscope can resolve to about 200 nm and advanced modern instruments may approach this. Recent usage confines use of the term nanocrystaline to crystals less than 1 μm, so the name is reasonable anyway. See WP articles on microcrystaline, nanocrsytaline, optical microscope. Wickwack 124.178.49.220 (talk) 00:42, 31 May 2013 (UTC)[reply]

So, it's a double misnomer - it is neither on the nanoscale, nor is it crystalline. According to the article, it is a microgranular solid sol, wherein the continuous phase is amorphous, and the dispersed phase is paracrystalline. From what you're saying it seems that the answer to my question is that the term is retained for historical reasons. True? Plasmic Physics (talk) 01:49, 31 May 2013 (UTC)[reply]

Can we invent something here? (Ice thickness and ultrasound)

I just happened across a National Geographic program "Life Below Zero" in which people were describing all the relatives they'd lost to thin ice on the Yukon River. It occurred to me that you ought to be able to measure the thickness with ultrasound, an idea which has apparently found traction on the Web before. [1][2] My thought is that what you'd want would be a relatively low cost, very compact device that can be attached to the bottom of a shoe as a cleat, which would dig into the ice with each step (potentially extracting energy to recharge itself), emit one ultrasonic click, measure the time to reflect, and emit a tone and/or a colored flash of light whose pitch is proportional to the thickness. (with various settings for convenience like omitting the flash/sound if the thickness remains large and unchanging)

Now, those two forums both had people with some degree of technical skill who made it a substantial bit of the way toward an invention, for example identifying 5 Mhz transducers that sell for $100 on Ebay. But they didn't get there; no individual seemed able to bring the ball home. (I wonder if these things get filed away under "someday maybe I'll patent it" which is a joke, because nobody wants to bet the legal costs for the random and unlikely reward; but fame, glory, and above all the blessings of somebody not drowned offer alternate paths to value) Anyway, I would think that the Science Refdesk by itself, and Wikipedia in general, have the pool of people and the collaborative research structure needed to pull off something like this for real. My question is then, do you think we'd have a chance to succeed, would people be excited, should we try something (not necessarily this) and if not ... is there any other place on the Web where people are trying to crowdsource invention? Wnt (talk) 04:10, 31 May 2013 (UTC) |}[reply]

We should start a project page on Wikipedia for these sorts of things. Count Iblis (talk) 13:12, 31 May 2013 (UTC)[reply]

We can't solve the problem for you or start your project or make this gizmo - but we can try to answer your questions:

do you think we'd have a chance to succeed? - I don't see any obvious technological reason why you couldn't make a small, hand-held, battery-operated ultrasound gizmo to measure the thickness of ice. This machine (for example) retails for $550 or so and can measure the thickness of many kinds of material using ultrasound - it's physically very much like the thing you imagine - and indeed might already do what you want. However, one limitation it has is that the top and bottom surfaces have to be parallel - and from what I can see here and here - that is most certainly not the case. So you might need a more sensitive receptor and fancier software to get a reasonable answer. On the other hand, that device is accurate to a tenth of a millimeter - and you only need an accuracy of around an inch!
would people be excited? - It's hard to tell. This article (and several others I dug up via google) suggest that around 8,000 people fall through ice every year and drown - so it's a significant risk. But it's hard to tell how excited people would get about a device to prevent that.
should we try something (not necessarily this)? - There would be significant development and testing costs - and the market for the device is unknown. The price (we imagine) could be in the $500 and up range. There would be considerable risk involved in spending the money on the development and then finding that nobody wants to buy it.
and if not ... is there any other place on the Web where people are trying to crowdsource invention? - This would be a great thing to crowd-fund. If you used something like Kickstarter to raise the development money, you'd know in advance how many people would buy the thing. As for getting the design work done, I suggest you read our Crowdsourcing article.

I wonder whether it would just be easier to sell a small device that comprises an electric drill with a thin, 8" long drill bit with marks along the length that show how deep you've drilled. I suspect that would be much easier than messing around with ultrasound.

SteveBaker (talk) 13:52, 31 May 2013 (UTC)[reply]

To be clear, I don't regard myself as having the qualifications to advance such a proposal for funding on my own behalf. Also, I don't really understand Kickstarter - I've seen some people call it a lottery like YouTube where people almost never win funding, yet reading through the proposals it seems like mad things are funded with only the scantiest of information or qualifications. But not having a background in engineering, I feel like going to get crowdsource funding on my own would be dishonest, and that can't pass. The magic of Wikipedia has been that people who would never write an article about a topic on their own are somehow able to get together, complement one another's weaknesses, and produce something worthwhile. I wonder if that can be duplicated in a new context. Wnt (talk) 17:01, 31 May 2013 (UTC)[reply]

Kickstarters are definitely not a lottery. I've run three of them - the first failed (for very good reasons) the other two raised a total of $100,000. If you have a good idea and a solid financial plan for making and shipping the product, you can and will make a respectable amount of money. Around 45% of projects make their goal. SteveBaker (talk) 20:30, 1 June 2013 (UTC)[reply]

You also have to remember that a number of those drownings occur while crossing ice on snowmobiles, dogsleds, or in cars and pickup trucks. Your device would have to work very fast and at a distance to help in those cases. Rmhermen (talk) 15:31, 31 May 2013 (UTC)[reply]

The idea with the first device was that if you can make it small (and I don't know a theoretical reason why you can't, but Steve's is too big I think) then you could put it on the bottom of a boot and have it take a reading with each step. I would think the same thing could be done with the strut of a snowmobile, but admittedly, it seems less plausible. Wnt (talk) 17:01, 31 May 2013 (UTC)[reply]

Another problem might be you would want to know the thickness of the ice ahead of you, not the bit you are currently standing on. Astronaut (talk) 17:35, 31 May 2013 (UTC)[reply]

Well, the people in the show were walking out nervously, listening to how the ice creaked under their feet, which is directly comparable. Ideally yes, it would be nice to know the other measurements as well - I wonder whether there's a possibility to use terahertz radiation to measure ice thickness at a distance? Wnt (talk) 18:42, 31 May 2013 (UTC)[reply]

According to the Planet Earth series, a crevasse detector that sensed the electrical properties of the ice (not explained in any detail, but probably a capacitance sensor or eddy current sensor) was tested in Antarctica circa 1960. It didn't work well, giving many false alarms -- but with modern technology, a sensor using terahertz radiation might (or might not) achieve better results. 24.23.196.85 (talk) 00:25, 1 June 2013 (UTC)[reply]

Ice stalagmite (or something)

I opened my freezer earlier today and saw something strange. The ice tray in the picture to the right is kept in the door of the freezer, but the strange thing is that it has a sharp, almost stalagmite-like protrusion near its center that I can't explain. My first thought was that it may have been caused by water dripping from above (like an actual stalagmite), but I'm not even sure that process would work with water alone (stalagmites are collections of dissolved minerals). The inside of the freezer directly above the tray doesn't have any obvious evidence of ice melt, and was fairly dry. (Also, it's hard to see in the picture, but the protrusion is off-vertical by twenty or thirty degrees, which would seem to be an odd angle if that's the cause.) Does anyone want to take a shot at this? Evanh2008 ^{(talk|contribs)} 09:32, 31 May 2013 (UTC)[reply]

Weird isn't it? But all is revealed at ice spike.--Shantavira|^{feed me} 09:40, 31 May 2013 (UTC)[reply]

And so it is. Thanks much! Evanh2008 ^{(talk|contribs)} 09:55, 31 May 2013 (UTC)[reply]

Five star question and answer! μηδείς (talk) 16:04, 31 May 2013 (UTC)[reply]

PCE and BTEX remediation

Would the use of SPH to remediate PCE be dangerous in a gas station? see: http://www.currentenvironmentalsolutions.com/WS/WS_21_WA_LAKEF.PDF Specifically, would the use of electricity in the soil cause the gasoline in the underground storage tanks to catch fire? Would it cause BTEX contaminants in the soil to burn? There is also BTEX contamination at the site. By the way, I am not actually trying to remediate a gas station. This is for a school project. It is an entirely fictional site. — Preceding unsigned comment added by 99.146.124.35 (talk) 15:50, 31 May 2013 (UTC)[reply]

Also, what is the cheapest in-steiu oxidation agent avalible on the market for BTEX remediation?

You must be VERY careful using any thermal (or electrothermal) process at a PCE-contaminated site -- excessive heating could decompose PCE with the formation of mustard gas. That said, mild heating such as that used in SPH is generally safe, and will NOT cause BTEX to ignite. Likewise, the gasoline in the storage tanks should not catch on fire (even though the tanks themselves can get quite hot) because air is normally excluded from them. 24.23.196.85 (talk) 00:41, 1 June 2013 (UTC)[reply]

Note, however, that SPH relies on moisture naturally present in the soil, so if the soil is dry it will not work. If that's the case, then direct steam injection is the way to go. 24.23.196.85 (talk) 00:45, 1 June 2013 (UTC)[reply]

Is the size of the two testicles remain same throught whole life?

Is the size of the two testicles remain same throught whole life? — Preceding unsigned comment added by Titunsam (talk • contribs) 18:35, 31 May 2013 (UTC)[reply]

According to our article, Testicles increase in size considerably at puberty. AndyTheGrump (talk) 18:38, 31 May 2013 (UTC)[reply]

After which time they should be in the ballpark (pun totally intended) of 2-3 inches in length and 1 inch in diameter, though there is considerable variation in what can occur even in healthy individuals and the right testicle tends to be slightly larger than the left (which none-the-less tends to hang lower; they're wacky pairs, those guys!) Snow (talk) 01:11, 1 June 2013 (UTC)[reply]