comparing Nikon immersion oils

August 27, 2014 at 2:53 pm | | everyday science, review

I typically use Nikon type NF immersion oil. But I hate the dropper that it comes in, and I’ve recently been having trouble with the oil crystallizing, especially if I aliquot it to smaller dropper vials. So I decided to compare the different oil types available, namely A, B, 37, and NF. (Type 37 is sometimes called type B 37.) Note that types B and 37 are actually Cargille part numbers 16484 and 16237, respectively.

A B 37 NF montage

See full slide deck here.

My conclusion: Use type A for routine imaging (the dropper is much easier to use and it’s less stinky than NF). For samples at 37 C or single-molecule imaging, use type NF.

stop…

August 20, 2014 at 12:31 pm | | nerd

hammer time

Coherent Obis Galaxy review

August 1, 2014 at 10:50 am | | hardware, review

We recently purchased new lasers for our TIRF scope. I wanted the flexibility and low cost of a home-built laser combiner, but also I wanted the ease and stability of a turn-key laser box. I stumbled upon Coherent’s Obis Galaxy combiner, which uses up to 8 fiber pigtailed lasers and combines the emission into one output fiber. What I really love about the idea is that you can add lasers in the future as your experimental needs grow. (Or your budget does.)

The other aspect I love is that it’s just plug and play! If I were on vacation when a new laser arrived, anyone in lab should be able to add it to this system.

2014-07-03 15.22.03

We also purchased the LaserBox, which supplies power, cooling, and separate digital/analog control to 5 lasers.

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The new system just sits on the shelf. It’s tiny:

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Here it is in action. The lasers were being triggered and sequenced by the camera and an ESio board, so they were running so fast I had to jiggle my iPhone in order to see the different colors.

One problem that I have faced is that the throughput is lower than spec (should be 60%+, and it’s down at 40%). Coherent is going to repair or replace the unit. And fortunately, we’re only running the lasers at 10% or less for most experiments currently, so there’s no rush to get the throughput higher!

If you’re ever in Genentech Hall UCSF and want a quick demo, drop me a line!

Pro:

  • Flexibility to add laser lines or upgrade lasers in the future at no additional cost (besides the pigtailed laser itself) and no downtime
  • Super easy installation
  • Cheaper than many of the other turn-key boxes
  • No aligning or maintenance needed
  • Each laser can be separately triggered and modulated (digital and/or analog)
  • Replaceable output fiber if it gets damaged (although it might not be as high-throughput as the original fiber)
  • Small and light, so it’s easy to find a place for it in any lab

Con:

  • No dual-fiber output option
  • Two boxes and some fibers going between the two makes it a little less portable than some of the other small boxes
  • No space to add optics (e.g. polarizers) in launch
  • Fans for LaserBox are not silent
  • Power and emission LEDs are too bright

Bottom line: I’d definitely recommend the Galaxy if you’re primary goals are color flexibility and simplicity. If you want more turn-key (and probably stability, but I can’t speak to that yet), there are other boxes to consider: Spectral ILE, Vortran Versa-Lase, Toptica MLE, and so on. Also, if you needed two (or more) fiber output, the Galaxy doesn’t have that option.

home-made plasma cleaner

July 23, 2014 at 12:52 pm | | everyday science, hardware, science@home, stupid technology

I really want a plasma cleaner, for cleaning coverslips and activating glass for PDMS bonding, but they cost thousands of dollars. I thought that was a lot of money for a glorified microwave. So I made my own.

Drill a few holes in glass:

2014-03-10 11.16.58

 

Make a PDMS seal (thanks Kate):

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Glue the chamber:

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We’re ready to go!

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Fill the chamber with argon, evacuate it, turn on the microwave oven, and … voila! … a plasma:

2014-07-17 12.54.18

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Below are slides before and after (right) plasma treatment. You can see the contact angle of water is dramatically reduced.

2014-07-17 13.14.40

It works!

Well, not really. I found that the plasma really only stays lit with argon. When I flow air in, it extinguishes, but also burns some of the rubber hoses. That adds more dirt to my slides than I want.

Conclusion: don’t do this at home. :)

(Well, that might be a little harsh. It does work well to bond PDMS to glass. And I’ll try a longer etch sometime to see if it will ever clean the coverslips.)

checklist of unusual phenomena

July 22, 2014 at 1:40 pm | | nerd, stupid technology

AKA “troubleshooting.”

image

eyepiece laser safety filter and 3D printing

July 8, 2014 at 3:57 pm | | hardware, lab safety

With TIRF and lasers on many fluorescence microscopes these days, there’s a huge risk of seriously damaging your vision. Not so much from a stray beam (which is probably diffuse or your blink reflex will be faster than the damage threshold), but more from looking in the eyepiece without the proper filters in place. A reflected laser beam focused with the eyepiece lenses right onto your retinas can be vary damaging.

(That happened a Berkeley a few years ago, and EH&S asked everyone to take the eyepieces off their TIRF scopes. I removed one, so that you’d only lose one eye.)

Interlocks between your scope port setting and your laser is one option. But that means you can’t ever look at your sample with your eyes (at least the fluorescence). The elegant solution it to put a multi-band emission filter in your eyepiece tube to block any laser light:

eyepiece laser safety

I got this idea from Kurt, who even designed a filter holder that you can 3D print. I modified that part for one that would fit in our Nikon TE2000.

2014-05-13 19.28.12

I also printed some other parts for our TE2000. After we upgraded our epi illumination source from a Hg lamp to a Lumencor Spectra-X LED, we no longer needed the ND filter sliders on the illuminator tube, because the LED intensity is easily controlled by software. I’ve always hated those sliders, because they are easy to accidentally knock into the wrong position. That, and they aren’t encoded into the image metadata, so you have no idea what slider settings you had when you look at an image 3 months later!

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So I removed the ND sliders and replaced them with a nice plug to block the light.

I have my 3D designs on the NIH 3D Print Exchange.

thorlabs lab snacks boxes for arduino enclosure

July 3, 2014 at 7:38 pm | | everyday science, hardware

On the topic of hardware syncing, I figured I should boast about my very fancy Arduino enclosure. I used a Thorlabs Lab Snacks box (one of the Great Boxes of Science):

2014-06-11 18.17.49 2014-06-11 18.17.33

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Of course, Nico makes beautiful laser-cut boxes for his Arduino, and Kurt has a nice 3D-printed box. But I think I’ll stick to this reduce/reuse/recycle approach. :)

UPDATE: I guess I’m not the only one. Labrigger posted a similar pic!

UPDATE 2: I made a bigger one to fit two Arduinos:

2014-08-07 14.07.19 2014-08-07 14.10.30

on the importance of hardware syncing

June 10, 2014 at 9:42 pm | | hardware, software

Before hardware syncing:

After:

For more details: https://micro-manager.org/wiki/Hardware-based_synchronization

EDIT: And now incorporating a Sutter TLED transmitted light:

electronics company

June 9, 2014 at 4:12 pm | | hardware, stupid technology

assmann

speck of dust

April 18, 2014 at 10:43 am | | crazy figure contest, history, literature

The scope room dustiness post reminded me of the hilarious story of the first report of second harmonic generation of a laser. The authors presented a photographic plate that showed the exposure the main laser beam, as well as a “small but dense” spot from the doubled beam,

shg dust

See the spot? You won’t. Because the editor removed the spot, thinking it was a speck of dust on the plate. Ha!

When I first heard this story, I didn’t believe it. I assumed it was a contrast issue when the paper was scanned into a PDF. So I went to the library and found the original print version. No spot their, either!

That really made my day.

reduce scope room dustiness

April 15, 2014 at 11:17 am | | hardware

I installed this simple dust filter over the air input register in our microscope room to (hopefully) reduce some of the excess dust. It also has the benefit of directing the air flow away from the microscopes, so I hope it will also reduce sample drift.

dust cover

I’ll update you in a few months if it seems to be working.

am i finished using Papers?

April 4, 2014 at 1:39 pm | | literature, software

I’ve been using Papers for years. When Papers2 came out, I was quick (too quick) to jump in and start using it. It’s worst bugs got ironed out within a couple months, and I used it happily for a while. Papers2 would let you sync PDFs to your iPad for offline reading, but it was slow and a little clunky. Papers3 library syncing is not for offline reading and it is VERY slow and VERY clunky. And it relies on Dropbox for storage. The plus of this is that storage is free (as long as you have space in Dropbox); the downside is that they syncing isn’t clean and often fails.

Mendeley has proven itself the best at syncing your library and actual PDFs to the cloud (you have to pre-download individual files for offline reading you can sync all PDFs in iOS in settings). Papers PDF viewer is still better, but it’s not worth the hassle: Mendeley syncs cleanly and the reader is fine. Not only that, but Mendeley has sharing options that make managing citations possible when writing a manuscript with co-authors (as long as they’ll use Mendeley).

Mendeley is also better than Papers at automatically finding the metadata for the paper (authors, title, abstract, etc.). The program simply works (most of the time), so I’ve given up and finally started using it. Almost exclusively.

PubChase syncs with Mendeley and recommends related papers weekly. (Update: the recommendations update daily, and they send out a weekly email with updates from that week.) They also have some pretty nice features, like a beautiful viewer for some journals and alerts when papers in your library are retracted.

Readcube still has the best recommendations. And they update daily, unlike PubChase’s weekly. And you can tell which recommendations you’ve marked as read, so it’s very quick to scan the list. But that’s really where Readcube’s benefits end. The enhanced PDF viewing feature is nice (it shows all the reference in the sidebar), but not really worth the slow-down in scrolling performance. The program is just clunky still. (I thought Adobe was slow!) And there’s no iOS/Android app yet. It’s on its way, allegedly, but I need it now! Readcube is really taking off, so maybe in a year it will be perfect. But not yet.

Edit: Readcube has a new version of their desktop application. Maybe it’s faster? Wait, did the references sidebar disappear? No, wait, it’s there. Just not on by default.

2013 Nobel predictions

September 26, 2013 at 10:46 am | | nobel

The Curious Wavefunction, Thompson-Reuters, ChemBark, and In the Pipeline have all started making Nobel Prize predictions for 2013. Last year, I correctly predicted Kobilka for GPCRs. In 2010, I got Heck and Suzuki. (You can find my previous predictions here: 2012, 2011, 2010, all Nobel posts.) Here’s this year’s stab at it…

Chemistry

Moerner and Orrit for single-molecule spectroscopy. Zare could easily be #3. Now that single-molecule imaging is effectively a routine tool in biophysics and single-molecule superresolution techniques like PALM/STORM are all the rage, it’s high time for a prize for this science. [FULL DISCLOSURE: I did my PhD with Moerner.]

Kris Matyjaszewski and Jean Frechet for polymer synthesis. Frechet invented chemically-amplified photoresists and developed dendrimer synthesis. Matyjaszewski was awarded the 2011 Wolf Prize. (Of course, others were involved in both discoveries.)

Al Bard and Harry Gray for bioinorganic chemistry and electron transfer. Both won Wolf prizes in the last decade.

Medicine

Gero Hütter for curing AIDS. Once.

Art Horwich & Franz-Ulrich Hartl for chaperonins. Unlikely a chemistry Prize, because GPCR won last year, and they probably won’t do another biomolecule this year. They won the 2011 Lasker Prize.

Ron ValeJim Spudich, and Mike Sheetz for biomolecular motors. Remember, they won the 2012 Lasker Prize! Maybe a chemistry prize, but same issue as with Horwich and Hartl above.

Carl Djerassi for the Pill. Unlikely, because they gave a prize for test-tube babies a couple years ago, and that would have been a perfect time to include Carl.

Jim AllisonEllis Reinherz, John Kappler, and Philippa Marrack for the discovery of the T-cell receptor. Oops, that’s too many people. Might not happen for that reason.

Physics

John Pendry and Steve Harris for cloaking and nonlinear optics.

Peter Higgs for that boson.

Peace

Bill and Malinda Gates Foundation for malaria and vaccine work.

George W. Bush for PEPFAR funding in Africa, now that AIDS rates in children are lower.

readcube and deepdyve update

June 6, 2013 at 7:48 am | | literature, science community, software

I just wanted to reiterate how great the ReadCube recommendations are. I imported all my PDFs and now check the recommendations every day. I often find great papers (and then later find them popping up in my RSS feeds).

Also, I wanted to let folks know that DeepDyve, the article rental site, is now allowing free 5-min rental of journal articles. Try it out!

block?

April 29, 2013 at 9:15 am | | science and the public

Sidewalk infographic fail.

2013-03-22 14.55.14

You think Stanford would know how to spell Felix Bloch’s name.

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