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The Academics Thread

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9 hours ago, Cancer said:

Ceramic leaches into the crucible?  Woof.  What acid is this?

 

Specifically, lead from the ceramic (or maybe just the glazing) leaches in. We're using hydrochloric acid (5% by volume) and nitric acid (2.4% down to 0.12%). Any concentration of either acid that will dissolve the ash residue will also pick up inconvenient (5-10% compared to the sample) levels of lead in either ceramic or nickel. But not in platinum.

 

For the unfamiliar, a platinum crucible is a little smaller than a shot glass and costs about $2800. Lids are an additional $400.

 

 

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Huh.  I would have thought crucible manufacturing tech would be able to exclude even trace amounts of lead.  Considering the lengths to which CCD manufacturers have to go to exclude actinides and their decay products (and ideally, spallation and fission products, but that's much harder -- I'm glaring at you, silicon-32) from the silicon boule in order to make a detector that won't be measuring its own impurities decaying, that sort of requirement isn't that exotic.

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It's probably also not something manufacturers worry about at $2 a piece.

 

It's worth noting that the samples were analyzing are already very low in lead to begin with. We're talking 10 to 30 parts per billion. The ceramic crucibles are leaching about 2 parts per billion, which isn't much, except in comparison to what we're trying to measure. At levels that low, even 2 ppb gives an unacceptable noise to signal ratio.

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Yeah, I overlook that there's enough of a market for chem lab stuff that there's manufacturer inertia.  In astronomy, everything is a one-off so it's all custom-made to order.

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Random Yokel: "Gee, it must be nice to be a teacher and get 3 months off every year." 

 

Me: "I respect and appreciate your constitutional right to free expression, but if you don't walk away right now, I'm gonna punch you in the throat."

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Hmm, the wife's last day was end of May and she starts back next week.  Plus, she has to start ordering stuff and preparing this week.  She is in an engineering program so that means 3-4 weeks of training classes at different tech colleges every summer.  Also, she has an engineering club for her students that starts end of summer and occupies after school every couple weeks.  Then, there is grading papers and preparing lesson plans on Sunday evenings and after school.  Oh wait, then there's also general/random school activities and extracurriculars that start after school that all teachers are expected to participate in at some point.

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On the fourth day of Professional Development, we have faculty meeting/curriculum training in the morning, followed by department meetings in the afternoon.

 

I'm giving presentations in both.

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On 7/5/2019 at 10:16 AM, Cancer said:

This is also a Huge blow to future games design! Supposedly Champs was born during one such lecture! Personally I did all my "homework" during lectures. I read the book, so I seldom heard something worthwhile. I only payed attention to math written or projected on the board/screen.

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Only people who've had run-ins with professional astronomy will get this ...

 

AIPS and FITS are 40 years old

 

AIPS is a reduction and analysis system for radio astronomy data.  FITS is the format for astronomical data of all types; if you've messed with real data in the last third of a century or so, then you have had to at least read FITS files.

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One of my favorite things to do is to work out a problem in detail for my class . . . and then ask them, "Now tell me why this can't possibly be the right answer."

 

:eg:

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