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Feb. 9th, 2004 08:16 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
catsittingstillIt has been ages since I posted--not because nothing is happening but because so much is happening that I keep running out of time.
Tuesday my car broke down. I called AAA (glad I had it) and had it taken to the nearest mechanic who answered the phone and said "yes I can see it today." It turned out that the distributor cap was worn out--easy repair, but the part had to come from Knoxville so I didn't get the car back till late afternoon. I walked home from the mechanic (3 miles) only to find that I'd left *all* my keys, not just my car key, at the mechanic's place. Fortunately my landlord (who lives next door) was home and gave me a lift back to the mechanic's to reclaim the rest of my keys. In the meantime, since I would be home all day after all, I called the furnace guy back and said he could do the mantainance today if he was free. Hmm. I had no idea this house had air filters I was supposed to change once a month. They were *filthy*. We've been living here since August.
I had icing problems all week with the cold stream of the diffractometer. The cold stream is a draft of dry nitrogen at -180 degrees C that blows over the crystal all the time it's on the diffractometer. It keeps the x-rays from damaging the crystal as much so that it lasts longer in the x-ray beam. Unfortunately it's a finicky little beast--if it's not set *quite* right water vapor from the room air can freeze onto the crystal--and water crystals (ice) scatter x-rays at least as well as protein crystals do. I spent much time on the phone and sending e-mail to the company that makes the cold stream and learned that the air compressor that separates the nitrogen from the room air, and dries it, has a whole bank of filters which need to be changed on a regular basis and nobody in the lab can remember the last time it was done. Hmm. I'm starting to see a pattern here.
Friday I discovered that what I'd thought was an oil glob in one of my protein crystallization trials was actually a huge (well, okay, 0.3 millimeters--huge by protein crystal standards in my experience) single crystal. This is very rare--crystallization trials are kind of rough attempts at crystallizing proteins--a condition that works usually gives you lots of little crystals, or crystals that are intergrown or stuck together in fans or unsuitable for analysis for other reasons. They give you a starting point that you then painstakingly refine to find conditions that give large single crystals.
My boss had me try some of the crystallization solution by itself to see if it would undergo a glass transition (become solid without becoming crystalline--a function of freezing very quickly and of containing a cryoprotectant--a substance that prevents the first tiny ice crystals from forming (nucleating)). It seemed to--it "froze" clear instead of turning white. So my boss, who is always in a hurry, wanted to put the crystal into the cold stream. Well, the whole thing turned white in a flash. Bad sign. We must have messed with it for an hour and a half, taking it off and putting it on again, adding glycerol (a common cryoprotectant) to the drop and putting the crystal back in it to soak for a minute, shielding the crystal from the cold stream with a business card (we keep one in the diffractometer room for precisely this purpose) to let it melt... finally the boss touched it with the card by accident, and that was that. The little thing fell right out of its loop and we never saw it again. The boss thinks it was probably a salt crystal anyway. I'm going to have to try to get another one--but this time I'm damn well going to turn off the cold stream and do a room temperature mount. Before I waste crystals looking for a cryo condition (an additive that will let me freeze the crystal without generating water ice) I want to be sure it's a protein crystal.
I wound up spending all of Saturday working. But got today off as compensation and will get Friday off as well (probably).
I had my mando lesson today on account of having to work Saturday. Recording last week's lesson turned out to be very useful--I've listened to the whole thing about 4 times by now and I don't know how many times I've played through some of the musical sections. Today's lesson was a lot more talking and a lot less playing, though, so I'm not sure how useful the recording will be. We'll see.
Also I agreed to write some "free standing applications" for a physics textbook today. This is a fancy way of saying I'll be writing some examples of physical principles, especially of physical principles in biological systems, as a short paragraph and a photo (but I don't have to find the photo) in the margins of a physics text. It's a humble beginning as far as science writing goes, but it pays a little and it sounds like fun and it will be a line on the resume. I'm kind of excited, actually. Let's hope I think of some good ones.
In other news, I tracked down my voter registration card, and found my polling place. The primary's tomorrow. :-)
Tuesday my car broke down. I called AAA (glad I had it) and had it taken to the nearest mechanic who answered the phone and said "yes I can see it today." It turned out that the distributor cap was worn out--easy repair, but the part had to come from Knoxville so I didn't get the car back till late afternoon. I walked home from the mechanic (3 miles) only to find that I'd left *all* my keys, not just my car key, at the mechanic's place. Fortunately my landlord (who lives next door) was home and gave me a lift back to the mechanic's to reclaim the rest of my keys. In the meantime, since I would be home all day after all, I called the furnace guy back and said he could do the mantainance today if he was free. Hmm. I had no idea this house had air filters I was supposed to change once a month. They were *filthy*. We've been living here since August.
I had icing problems all week with the cold stream of the diffractometer. The cold stream is a draft of dry nitrogen at -180 degrees C that blows over the crystal all the time it's on the diffractometer. It keeps the x-rays from damaging the crystal as much so that it lasts longer in the x-ray beam. Unfortunately it's a finicky little beast--if it's not set *quite* right water vapor from the room air can freeze onto the crystal--and water crystals (ice) scatter x-rays at least as well as protein crystals do. I spent much time on the phone and sending e-mail to the company that makes the cold stream and learned that the air compressor that separates the nitrogen from the room air, and dries it, has a whole bank of filters which need to be changed on a regular basis and nobody in the lab can remember the last time it was done. Hmm. I'm starting to see a pattern here.
Friday I discovered that what I'd thought was an oil glob in one of my protein crystallization trials was actually a huge (well, okay, 0.3 millimeters--huge by protein crystal standards in my experience) single crystal. This is very rare--crystallization trials are kind of rough attempts at crystallizing proteins--a condition that works usually gives you lots of little crystals, or crystals that are intergrown or stuck together in fans or unsuitable for analysis for other reasons. They give you a starting point that you then painstakingly refine to find conditions that give large single crystals.
My boss had me try some of the crystallization solution by itself to see if it would undergo a glass transition (become solid without becoming crystalline--a function of freezing very quickly and of containing a cryoprotectant--a substance that prevents the first tiny ice crystals from forming (nucleating)). It seemed to--it "froze" clear instead of turning white. So my boss, who is always in a hurry, wanted to put the crystal into the cold stream. Well, the whole thing turned white in a flash. Bad sign. We must have messed with it for an hour and a half, taking it off and putting it on again, adding glycerol (a common cryoprotectant) to the drop and putting the crystal back in it to soak for a minute, shielding the crystal from the cold stream with a business card (we keep one in the diffractometer room for precisely this purpose) to let it melt... finally the boss touched it with the card by accident, and that was that. The little thing fell right out of its loop and we never saw it again. The boss thinks it was probably a salt crystal anyway. I'm going to have to try to get another one--but this time I'm damn well going to turn off the cold stream and do a room temperature mount. Before I waste crystals looking for a cryo condition (an additive that will let me freeze the crystal without generating water ice) I want to be sure it's a protein crystal.
I wound up spending all of Saturday working. But got today off as compensation and will get Friday off as well (probably).
I had my mando lesson today on account of having to work Saturday. Recording last week's lesson turned out to be very useful--I've listened to the whole thing about 4 times by now and I don't know how many times I've played through some of the musical sections. Today's lesson was a lot more talking and a lot less playing, though, so I'm not sure how useful the recording will be. We'll see.
Also I agreed to write some "free standing applications" for a physics textbook today. This is a fancy way of saying I'll be writing some examples of physical principles, especially of physical principles in biological systems, as a short paragraph and a photo (but I don't have to find the photo) in the margins of a physics text. It's a humble beginning as far as science writing goes, but it pays a little and it sounds like fun and it will be a line on the resume. I'm kind of excited, actually. Let's hope I think of some good ones.
In other news, I tracked down my voter registration card, and found my polling place. The primary's tomorrow. :-)
