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  1. Old Dog

    Activity 24 Effect of temp on amylase

    Having read the OCR tech notes, I'm only glad we do AQA. What's the point of being so precise with making up the amylase in a volumetric and then adjusting concentration to get a sensible time for the reaction to work. Waste of time! Students/teachers don't care what the final conc of amylase is...
  2. Old Dog

    Does anyone know if Betterequipped Buffer tablets pH 7 make a phosphate buffer solution?

    Phosphate buffer (in Biology at least) normally refers to a mix of 0.1M Citric acid and 0.2M Di-sodium hydrogen orthophosphate. Make up stocks and mix the two together as required and use a pH meter to adjust to required pH. I doubt you'll get an answer from BetterEquipped as I suspect they...
  3. Old Dog

    Practical using rooting powder?

    We do AQA and this is definitely not a required practical. We do run it every year though when they teach about asexual reproduction and cloning. Pelargoniums are good, don't really need hormone to root. They do appreciate an open compost - we add Perlite - and a small plastic bag over the pot...
  4. Old Dog

    Flower Dissection

    We use a variety of flowers depending on the season. Primulas are v. good, you sometimes get enough for whole classes on one plant if small flowered and you can plant them out later - if you have a flower bed on site or take them home! They also come in "male" and "female" forms depending on...
  5. Old Dog

    I hate to say Algal Balls again but......

    Finally got Algal Balls that work - yippee! Great culture advice from Peter S however I have one observation that I'd like to share. Set up Scenedesmus for bulk culture but failed after a week. Then saw thread suggesting using Spirulina powder, failed. Tried Chlorella powder, failed. Tried...
  6. Old Dog

    TST strips for autoclave

    I have always assumed that all autoclave tape only goes dark if you expose it to 121 deg for 15 mins, i.e. enough for most sterilization procedures. That's because I was taught this 35 years ago when I worked in a Uni lab. If there are two types of tape around, firstly what does the tape that...
  7. Old Dog

    Is this the beginning of the end for the Science Technician role?

    For me I think one of the key problems for us as a profession is the decreasing emphasis on the need for students to actually get off their stools and do some practical work. When the required practical details were published our department head was rather horrified at both the simplicity and...
  8. Old Dog

    Fermentation jar

    I assume this is required soon and you're not about to buy the proper kit for it - photo courtesy of Dr J. Therefore if faced with this request I'd probably use a demijohn. To get a proper anaerobic fermentation it needs to be airtight. Problem no. 1. Fit a brewing airlock and then you could...
  9. Old Dog

    Benedicts test...

    Yes and no. Have only managed a yellow colour when testing skimmed milk solution. I don't see how it would be possible to get a yellow solution using glucose and Benedict's only. The point is at low reducing sugar conc you get a small amount of Cu+ ions but you still have a lot of blue Benedicts...
  10. Old Dog

    Wrights stain

    We use Quink Ink using the following method. https://www.microscopy-uk.org.uk/mag/artsep15/ct-Quink-blood-stain.pdf
  11. Old Dog

    Minimum water bath temp for Benedicts test?

    We always use kettles so temp is going to be at least 80 - 5 mins should be plenty of time. If concentrations of reducing sugar are low then I think you might not get a positive test at lower temps. Gave up on using Bunsen's for water baths as we often have ethanol out at the same time for food...
  12. Old Dog

    Storage of Enzymes

    In my experience lipase doesn't seem to last well and if you accidentally leave some overnight at room temp it really stinks! I always make fresh. Trypsin also seems to lose it's potency over time so I have to test it before sending it out. Amylase - that's a different customer. The stuff from...
  13. Old Dog

    Re Using Visking Tubing

    Re-used is ok for basic experiments and if you're going to put a mixture of glucose and starch inside. However re-used doesn't work as well if you're digesting starch with amylase and then looking for diffusion of glucose (maltose really!). If you want a positive Benedict's test using the water...
  14. Old Dog

    OCR PAG 7.1

    Sterilised glass Pasteur pipettes if volume accuracy not critical (put cotton wool in teat end and load into beaker. Cover with foil and autoclave/pressure cooker), otherwise sterile 1 ml syringe. Put broth in McCartney or Universal so the syringe reaches.
  15. Old Dog

    Mammal Trap

    If you're going to use this to actually trap a mammal rather than just to demo the trap, don't you need a licence? Most wildlife that isn't a pest or an invasive is protected. We got rid of all traps some time ago so sorry cannot supply you with one.
  16. Old Dog

    Mouldy clinostat

    I always use cress or mustard on damp cotton wool in a small galipot. Attach this to the Clinostat with the help of a couple of large elastic bands. The cover will still fit over. After a week or so the seedlings are growing in all directions which is far more interesting than one sad broad...
  17. Old Dog

    Storage of Enzymes

    I'd agree with fridge for all of them, however when I started in my current job 14 years ago there was a tub of pepsin on the prep room shelf. It never failed to work and I sadly used the last of it this year. Admittedly my prep room never gets any more than warm but this stuff was amazing...
  18. Old Dog

    CLOSED - Science Technician with Chemistry Experience - Bath, Somerset Permanent Closing Date 29th April. Immediate start possible.

    The current post-holder works a 4 day 32 hr week. She arrives early and leaves mid-afternoon. The College is reasonably flexible over when you start/finish. Hours would be one aspect that would be negotiable but I would expect the new person would be asked to work a 5 day week. As for pay, we...
  19. Old Dog

    Job Vacancy in Bath

    Is there a specific group/part of the website where you can post job vacancies? We're just about to lose our Chemistry Tech of 18 years and we'd like to advertise to forum members if that's allowed.
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