It almost seems like you're interpreting "UV-C" to include the range from 360-380nm. There are apparently some results indicating that emitters in this range can be germicidal, if you use enough power and enough exposure time; is that where our disconnect is arising?

The Nichia page you linked lists only longwave emitters, with 365nm the shortest wavelength. I'm sure they have shortwave emitters, and maybe even samples for some of them, but if they aren't listed on the Web site, I'm not confident how much of a "product" they are to date.

Cree has never sold UV-C LEDs, as far as I can tell. They sold longwave emitters for a while, but then discontinued them.

I spent some time prowling around HaSun's list of UV LEDs. I haven't waded through every listing, but most of the emitters under 300nm seem to be in the range of 1.5mW or less; I found one ("New Technology!!!") that claimed 0.2-0.3W optical output power in the specs, but in the chart below, it said 0.2-0.3mW. WIth forward current of 20 mA and forward voltage of 7-8.5 V, getting out 200mW of anything would be quite the trick.

Again, we can see that the shortwave emitters exist, but it doesn't look like they're common enough or powerful enough to start appearing in products yet.

I'm flattered that you're reposting my links from below, but I think you're missing GP's point. None of those three links appear to describe units that are "commonly available" -- in one case, it's only engineering samples, and in none of the links do they say a word about pricing or actual availability (the last one claims "mass production", but doesn't back it up).

"UV lasers" are mostly 405nm, not really UV, and the quantum dots from TFA are firmly in longwave territory. So, GP's points stand.

Actually, 420 would be a bit too violet for this application. Cree's XR-E emitters seem to use a blue emitter centered around 450nm (pdf), coupled with a yellow phosphor -- blue + yellow = blue + (green + red) = white. That's how most "white" LEDs work. If you used a shorter-wavelength emitter, you'd need to downconvert all its output power, losing efficiency. By using a blue emitter, you pass some of the blue light, and downconvert just enough of it to yield the perceived color temperature you want.

Links, please? Last I checked, UV-C emitting diodes were essentially experimental items, with output power below 1mW, and sky-high prices. Feel free to ridicule me mercilessly if I'm wrong, but please post links; I'm a lot more interested in learning about UV-C emitters than in defending my hypothetical reputation.

This page crows about UV-C LEDs, but is conspicuously silent about output power (beyond calling it "stable"), availability, or price.

This page claims 5-10mW per device, adding that "limited release engineering samples are available today." The datasheet is mum on device lifespan.

This looks more promising -- 10mW per device, 10,000 hour life -- but where are the products, and where are the prices?

Obviously, I could be missing some products that are already shipping. But if you actually have a bank of UV-C LEDs that's been putting out enough power to kill algae in your aquarium for the last five years, it looks like a lot of electronics and physics journals would be interested in hearing from you. And so, as I said, would I.

We already have robust conventional LEDs that emit high power at comparable wavelengths (considered "longwave UV"). This wavelength is not especially useful for purification and sterilization. For that, you need UVC, in the range of 250nm and below. That's still difficult with anything other than a fluorescent emitter or an arc; solid-state emitters in that range have very low power and short life, at least last time I checked.

The other problem with very short wavelengths is finding packaging materials that will transmit and withstand them over long periods. Even longwave UV will cause materials to deteriorate over the lifespan of a solid-state emitter; UVC is much more harsh.

I just really enjoyed grad school too much to want to finish, and they eventually made it clear to me that I'd better defend soon or they'd kick me out. Of course, I also wasn't accomplishing nearly as much in the interim as the article's subject.

It's an inspiring story. All the same, my dissertation defense is something that I'm just as happy I won't have the opportunity to tackle later in life...

I'm actually curious to know why that was modded down. It's a point that many have made.

Including women ... https://youtu.be/w__PJ8ymliw?t...

Should women be given free choice or not? One wonders exactly what the social-justice crowd had in mind.

The vast majority of women choose to study social sciences. Men don't.

Should their freedom of choice be curtailed? Should we 'force' women to study something they're not interested in? Because if such inhibition of personal freedoms is not acceptable then perhaps we should stop treating these obvious gender-aligned differences in preference as "flaws", and start treating them as "features" of our species.

The social justice crowd would of course insist that it's all "nurture" and not "nature". But how many times must this absurd belief system be obliterated with logic for it to finally disappear? ---> https://vimeo.com/19707588

Instead of tweeting about bowl movements, you should get the maintenance folks to tighten the mounting bolts.

But maybe I don't want a language that turns on me.

Timothy - this poll is interesting because it speaks to people's perception of themselves.

Slashdot actually has these statistics. It'd be really interesting to go back and run the numbers, and see if the polling is inline with reality. We don't often have a way to verify the accuracy of any poll - but in this case, we do.

If you're spending that much to send them to a "better" school, the least they could do in return is proofread your posts for you.

Boy, some people just refuse to let go of legacy processors...

I remember sketching/doodling a hydrogen balloon with a fuel-cell panel stitched into it when I was in 9th grade. Of course, I didn't know much about the practicalities of fuel cells -- just that I probably couldn't afford the platinum it would require. And this was pre-TRS-80, so about the only thing it would have done autonomously was go up until it used up its hydrogen, then come down.

One must note that the ice sheet has **ONLY** existed for 10,000 years.

It's very important to stress this point, as those who do not understand geologic time are at risk of thinking that 10,000 years is a long time.

It's a nanosecond on the geologic clock.

This is a very young icesheet. It's loss is noteworthy, but does not have significance when viewed on macro timeframes.