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This is a very niche product, so feel free to move along.
The average molecular biologist spends 7.3 minutes per day defrosting frozen solutions. Typically, these are in standard 1.5ml microfuge tubes (Eppendorfs to you and I, if you are also a molecular biologist). Most biological reagents are
stored at -20°C.
The standard method of defrosting Eppendorfs is to hold them in the fist whilst being impatient. Occasional shaking, to and fro, slightly accelerates the defrostage, but does not look good.
Yes, you can use a dri-block or pop your tubes in a handy incubator or waterbath, but this is a pain.
What is needed, therefore, is a simple pop-up Eppendorf defroster. Powered by a USB connector for simplicity, it is rather like the bastard child of a vehicular cigarette lighter and a pop-up toaster. Simply pop the Eppendorf in, press it down, and it will be gently but speedily warmed until it reaches room temperature. Thereupon, it will pop up, ready to use.
bs0-brand productivity-enhancing buffer
http://www.nature.c...d_name=subjects_dna
[bs0u0155, Sep 28 2017]
Tiny Peltiers
http://www.customth...0-08RA_spec_sht.pdf
[bs0u0155, Sep 29 2017]
Call that tiny?
http://www.heat-man...en/1stagemiscro01_k
[MaxwellBuchanan, Sep 29 2017]
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Annotation:
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When the weather gets hot I ride the Moto Guzzi to and fro with artificial ice cold packs in my shirt pockets. |
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Perhaps you could hire a motorcyclist to ride around for you. No, strike that. |
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Why not just take you -20C tube and shove it up your ... |
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But it would defrost quite quickly ... |
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It would. However, the Health and Safety czars perpetually try to dissuade scientists from having hot (or even cold) drinks in the lab. |
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//The average molecular biologist spends 7.3 minutes per
day defrosting frozen solutions.// |
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The average cell biologist spends 73 minutes per day
defrosting frozen solutions... One tactic is to take the
two 50ml frozen falcon tubes and put one each in the
trouser pockets. It still takes a few minutes, so why not
get a little sun and a coffee? The growing damp patches
caused by the 80% humidity condensing on the front of
your jeans acts as a wonderful charity-mugger deterrent. |
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Anyhow. Just swap out your solvent, even fussy old DNA is
happy in antifreeze <link> |
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//It would. However, the Health and Safety czars
perpetually try to dissuade scientists from having hot (or
even cold) drinks in the lab.// |
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This sentence could end 10 words earlier. |
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No. A dean - in places that have one - is typically an elderly person with considerable experience but no actualy power. A czar, in the present context, is someone who is typically young and with no understanding of anything, yet who paradoxically has immense power over everyone else. |
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" One tactic is to take the two 50ml frozen falcon tubes and put one each in the trouser pockets. It still takes a few minutes, so why not get a little sun and a coffee? The growing damp patches caused by the 80% humidity condensing on the front of your jeans acts as a wonderful charity-mugger deterrent. " |
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The average home brewer spends an indeterminate amount of time bringing vials of yeast from refrigerator to room temperature in the same manner. Time estimates are uncertain at best, as usually by that time in the process much ale from the previous batch has been consumed. |
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My safety czar has authorized me to cover the kitchen in fire extinguisher product anytime I choose. She says she'd rather clean all that up than talk to the fire department. |
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Wait... what you're describing is an electrical device for
rapidly changing the temperatures within Eppendorf
tubes in a controlled manner. If only there were one
already in the lab? We used to have one, I think it became
a "shared resource" and as such all PCR now involves a
trip to Cleveland. |
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Actually, a USB-thermal cycler is easily doable.
You could do say, 1 tube with standard usb which are all
about an
amp nowadays, or use 2 ports. Certainly these Peltier
elements
<link><link> flow about a Watt, which for a 50ul PCR
reaction gets you 5C/second if you ignore the tube etc, so
say 3C/second? Are there problems associated with the
rate of change? |
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Anyhow, you need a little Peltier attached to the bottom
of a little aluminium tube holder, wrap in insulation,
place inside much larger casing which doubles as a
heatsink, maybe a relay. You can probably get away
without a temp sensor if you know enough about the
Peltier. The microcontroller, screen, transformer, casing
all unnecessary, control software trivial, it's already USB. |
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For a bit more oompf, a slightly more robust Peltier and a
chunky capacitor would solve the transient high power
demands. |
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With USB-C the power problem goes away and a full-spec
version is easy. Perhaps a little more messing with the
complex interface. |
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Thermocyclers generally take 0.2ml tubes, which defrost in a moment in your hand anyway. Plus they're bulky and not particularly cheap. I'm thinking of something cheap-n-cheerful for 1.5ml tubes, that everyone can have on their bench. |
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And yes, a USB thermocycler is doable, though it would be small and probably only take a few tubes. A reasonably fast 96-well cycler takes about 10A at 12V. |
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It sounds like you need a lump of plutonium with
holes drilled in it to accept the Eppendorf tubes.
Have this in a handy place on your lab-bench. Then
just drop the tubes in it for a few seconds and the
heat generated by the radioactive decay in the
plutonium will be enough to defrost the solution. |
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//What's needed obviously is a combination of dean
and czar// - clearly, a combination of a
DEan and a czAR is a 'Dear'... |
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Is a scientifically standardized defrost method needed? |
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That's an interesting question. |
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Some things are sensitive to the rate of freezing. For instance, if you're freezing live cells, the rate of cooling matters a lot. And for non-living solutions, the rate of freezing can affect how the solute partitions (slower freezing tends to concentrate the solute in the last-frozen part). |
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For defrosting, I'm not sure. In most cases it won't matter, but there are exceptions. For instance, if you're defrosting frozen bacteria, it's necessary (in some situations) to do so slowly, so that no part of the liquid gets much above zero degrees. The same is true for some temperature-sensitive compounds. |
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But, 99 times out of 100, you just want to defrost the solution quickly but gently. |
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Set up a lab-adjacent bakery and lab mice production
facility. Bakery bakes bread, mice chew eppendorf tube
sized holes in bread, bread is placed into glovebox,
eppendorf tubes are placed in fingers of glovebox and
fingers are inserted into eppendorf sized holes in bread.
Following removal of warmed tubes / gloved, hollows in
bread are filled with garlic butter and passed to me, for
recycling. |
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//But, 99 times out of 100, you just want to defrost the
solution quickly but gently.// |
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I think a big part of the problem is the success of the
Eppendorf tube. For those not in the know, it's a little
flip-top 1.5ml polypropylene container with a conical
bottom. They're cheap, everywhere and so are used for
everything. They were not designed for storage, or
melting/freezing, they were made so tough and relatively
thick because they needed to stand up to high G
centrifugation. There's probably a few things to be done
that could improve them, for one, I'd like to see harsh but
punitive tax imposed on companies that continue to make
such tubes in EXACTLY THE SAME COLOUR AS ICE. I
suspect millions a year are wasted because of invisible
tubes. You could also play with the properties of the
plastic to increase thermal conductivity, I know PTFE with
glass microparticles has been used to increase heat
transfer by 50% or so. |
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//EXACTLY THE SAME COLOUR AS ICE// The answer, therefore, is to make the ice a different colour. The pigments in some coloured Eppendorfs can, and do, leach into solutions. We (and by that I mean me and some other people) spent a week trying to find out why our 4-colour supersensitive fluorescence assay was giving a huge signal in one channel. It was pigment leaching from the polypropylene. |
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bilayer plastic, color on outside |
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Eppendorf tubes are produced and used by the gazillion, and presumably are made by injection moulding. Cheap and simple is good. |
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//EXACTLY THE SAME COLOUR AS ICE// |
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Pure ice doesn't have a colour - it's transparent, |
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<balancing hands> meaning ... pedantry , pedantry...meaning </balancing hands> |
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