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The science of mouldy soup

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TMA04

I must start this blog post with a bit of a "hurrah!" I have received my mark for TMA04 (Book 4: Chemistry). Drum roll... I got 92% - even with the "discussion" about one of the questions, and its ludicrous wording and requirements.

So, I'm very chuffed indeed. I understand chemistry. Or at least, I understand the basics, which will stand me in good stead for Book 5: Life - and, I hope, level two of my journey.

Mould

Activity 2.1 of Book 5 required me to investigate fungal particles in the air. In my kitchen, to be precise. So an experiment was undertaken. Bear with me... it's aces.

The aim of this investigation was to estimate the density of fungal particles (spores) in the kitchen by exposing an appropriate growth medium (Sainsbury's Basics tomato soup - I'm a cheapskate!) to a known volume of air, and then seeing how many fungi grow on it.

Equipment

Small can of Sainsbury's Basics tomato soup

Rectangular plastic container

Paper and sticky tape to label container

Cling film

Ruler.

Experimental design

The container needs to be wide enough and deep enough to accommodate the soup, plus a reasonable volume of air. About half a litre should be plenty. A rectangular container will make it easier to measure and calculate the volume of air under the cling film.

By washing the container thoroughly, and drying it upside down, the likelihood of contamination will be reduced. To ensure that nothing else gets inside, the soup will be transferred to the container quickly, and then immediately covered with clingfilm. A second layer of clingfilm will be used to make the container airtight, thus preventing anything else entering the container.

The volume of air can be measured by multiplying together the length and width of the container, and then multiplying by the depth of air from the clingfilm to the surface of the soup.

It should be kept out of reach of children and animals, and where it is unlikely to be disturbed. Although I can't imagine anyone - husband or cats - would look at that and think: "Ooh yum! I'm a bit peckish" and then dive right in...

How long should I leave it? Well, how long's a piece of string? That will depend on how quickly mould forms on the soup. A week or so should be fine.

I will record the start and finish date and time, and record when fungus first begins to appear, and when it stops increasing.

What should I do with the container and its contents afterwards? Well, the OU recommends that I throw away the whole shebang - for health and safety reasons (excuse me while I stop laughing); however, I will dispose of the mouldy soup in the toilet, rinse the container into the toilet, then put it through the dishwasher for a thorough wash. I am not throwing away a perfectly good Tupperware container! That's going to have my lunch in it tomorrow.

Practical procedure

The container was thoroughly washed and left upside down to dry. When it was dry, the can of soup was opened and quickly poured into the container. The soup was immediately

covered with two layers of clingfilm, and made airtight.

The experiment was labelled "Biohazard: not to be eaten", and the date and time recorded

(May 31, 2011 at 7.30pm). The container

was placed out of the reach of the cats, and left where it was unlikely to be disturbed.

biohazard.jpg?w=300
Biohazard: mouldy soup

The volume of air in the container was measured:

Depth from clingfilm to surface of soup: 3.0 cm

Width of container: 13.5 cm

Length of container: 18.5 cm

Volume    = 3.0 cm x 13.5 cm x 18.5 cm

= 749.25 cm3

= 7.5 x 10-4 m3 (2 significant figures) Note: the corners of the container were rounded, so this figure is approximate.

The first mould began to appear on June 4 and were tiny white spots (about 1 mm in diameter), mostly around the edges of the tub.

On June 5, the white spots had grown to a diameter of around 3 mm to 4 mm, with 1 mm green/blue patches in places. More areas of growth had appeared. Condensation also appeared on the clingfilm, which made observations a little awkward.

My mould was respiring! I was so proud. My very own baby mould; they grow up so fast.

By June 9, no more spots were appearing. And it's probably a good thing, because it was getting a little crowded in there, and the patches were beginning to fight among themselves. I did NOT want to have to step in there and break anything up.

Results

fungal-particles.jpg?w=300
The Mould Boyz

Seventeen separate areas of mould were counted. Most of the mould was clinging to the edges of the soup on the container, with a few patches in the centre. The patches in the centre resembled blisters lying just on or beneath the surface. They were milky in appearance, and slightly jelly-like, measuring 0.5 cm to 1.0 cm in diameter. Delicious.

The patches around the edge were either white, or white with green/blue areas. The white patches had stalks, while the green/blue mould was furry in texture. These patches measured around 1.5 cm to 2.5 cm across. I've seen this furry mould before; it normally inhabits the bit of sandwich you've just put into your mouth. You know this, because there's half a patch of mould left when you look at your meal.

Analysis of results

Each area of growth probably represents one fungus, which arose from one fungal spore. My result was: 17 fungal spores per 7.5 x 10-4 m3 air.

To find the number of fungal spores per cubic metre of air:

= fungal spores per m3

= 2.3 x 104 fungal spores m-3 (2 significant figures)

I could work out the total number of fungal spores in the air in my whole kitchen; but frankly, I'd rather not know! I'm quite happily living in blissful ignorance, and perpetuating the dastardly rumour that I am, in fact, a great wife who cooks, cleans, maintains her rather great bottom AND makes interesting conversation that does not involve mould.

Critical thinking

The density of fungal spores I obtained is almost certainly an underestimate of the true density. This does not make me happy. I thought 22,666 spores per cubic metre was quite alarming enough.

Assumptions were made that the number of fungal spores in the air are evenly distributed throughout the room; this is unlikely to be the case, especially with movement of air. It may be that not all the spores trapped in the container grew into patches of mould. It was also assumed that all spores had grown into mould when I ended the experiment; this may not be the case.

Further investigations

We were supposed to think about what else we could investigate. But really, the only thing that came to mind was the mating habits of fungus. I suspect I've been staring at a screen for too long...

My next activity involves researching Leontopithecus rosalia. Stay tuned!

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Blue hair, yellow sweater, big smile

An experiment to investigate light in the style of a pirate

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Edited by Vicky Fraser, Tuesday, 12 Apr 2011, 21:32

I have had a lovely weekend in the sunshine, much of which has been spent outside in our garden, under the beautiful cherry tree, on our new garden furniture. I've been pottering around, weeding the vegetables, planting more seeds, and watching the cats chase motes of dust.

In between, I've been studying hard - book 3, Energy and Light. I'm almost there; I've completed most of TMA03; all I needed to do was Activity 11.1 - Investigating Light.

Joe and I liberated a cardboard document box from his offices, and I planned my experiment. It is set out below, just as it is in my folder (with perhaps just one or two embellishments, and an extra instructive illustration). Some of the details have been changed and the first-person voice has been used because the write up was part of the assessment, and so cannot be made public for fear someone may plagiarise me. So some of this may or may not be true!

Investigating light: determining the wavelengths of spectral lines from an energy-saving light bulb.

Equipment

  • Diffraction grating (300 lines per mm)
  • Tungsten filament light bulb (40 W)
  • Energy-saving light bulb (11 W)
  • Lovely stripy table lamp (for the tungsten bulb)
  • Tall standard lamp (for the energy-saving bulb)
  • Large cardboard document box
  • Pieces of Amazon book cardboard
  • Gaffer tape
  • Sharp knife
  • Paper protractor
  • Blu-Tack
  • Black cotton thread
  • Red drawing pin
  • Dressmaker's pin
  • Eye-patch
  • Table
  • Dressing gown

Aim

To determine the wavelengths of blue, green and red spectral lines from an energy-saving light bulb.

Method

Having liberated the box from Joe's work in a ninja-style midnight operation, I cut a thin slit in it using the sharp knife. Joe took this off me, and did it properly with a minimum of blood spilled. I tidied the edges using gaffer tape. Gaffer tape can do anything: FACT. The table lamp containing the tungsten bulb was placed within, and Amazon cardboard was cobbled around the edges, in an attempt to prevent too much light from escaping and having a party where my spectral lines were supposed to be.

I had a gander through the diffraction grating, and this is what I saw - a continuous spectrum:

tungsten.jpg
This is an actual photograph I took *proud*
darkroom.jpg?w=300
Professional pirate dark-room. Eye patch provided.

Next, I needed to take a look at the spectrum produced by the energy-saving bulb. So I undid my gaffer-taped masterpiece, and fumbled the floor lamp with the energy-saving bulb under there. I couldn't quite manage to see the spectrum this time, so I created a dark-room, thus:

This created the ideal conditions to observe and photograph my diffraction spectrum - which was not continuous, and was in fact a line spectrum. Again, I photographed it:

energy-saver.jpg?w=300
Line spectra from an energy-saving bulb

All this was very pretty, but had to be interrupted by a trip to Charlie's to make me a longbow. You see, my marvellous husband (he of the fabulous presents) bought me A Big Piece of Wood for my birthday. Not just any piece of wood, mind; a piece of yew, laminated with maple and lemon wood. He, Charlie and I began the shaping of a (very) long bow. It's going to be grand!

Back to science.

Later, when darkness had fallen, I continued my experiment and set up my equipment. Leaving the box with the energy-saving bulb where it was, I stuck it down to prevent any disastrous movement, and placed a paper protractor about 50cm away. A drawing pin pierced the protractor, to provide an anchor point for the thread. The diffraction grating was placed upon the protractor at the axis. Thread was tied to the drawing pin and the dressmaker's pin, and all was ready. See:

experiment.jpg?w=199
Experimental set up.

This is where the eye-patch comes in. To measure the angle of diffraction for each spectral line, you have to line up the spectral line itself with the line on the grating and the thread upon the protractor. This is to be done with one eye, to prevent parallax error. I found myself unable to do this, and so had to use an eye patch.

Of course, it naturally followed that I had to conduct the rest of the experiment in the manner of a pirate. Grog was acquired, and duly consumed. Tables were swabbed, angles were swashed, and the thread was buckled. Much like my knees.

The experiment was a success! The wavelength of the blue, green and red spectral lines from the energy-saving light bulb were calculated as: 450 nm,  550 nm and 600 nm respectively. This isn't far off the actual wavelengths of light emitted by an energy-saving light bulb. Go and google it if you don't believe me.

This has been Science, by Vicky. I've enjoyed it; all that remains to be seen is how well my tutor likes the write-up... I do think that the eye patch was relevant. And the dressing gown.

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Blue hair, yellow sweater, big smile

On evaporation and blissful motion

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I am three quarters of the way through my two week precipitation experiment, which I have mostly been very good about recording. I totally forgot last night, which is a bit piss poor, to be honest. And my only excuse is that I was knackered. Oh, and we had to tighten the chain on my motorbike, which was the flappiest, crappiest thing ever. I’ve ordered a new one, and sprockets, because it’s pretty FUBAR’d.

Anyway – tonight’s precipitation was more interesting than of late; it’s been raining quite a lot, with the Met Office predicting floods because the ground is pretty saturated after the snow.

Vessel A (no funnel) now contains 20mm of water.

Vessel B (funnel) now contains 30mm of water. I also noted that the underside of the funnel was liberally coated with condensation. It’s been pretty breezy and dry today, so I am thinking that much of the water from vessel A upped and left. Either that, or my neighbours are playing silly buggers with my experiment (although it doesn’t smell of wee, so I should be thankful for that, I guess).

Evaporation interests me. I know how it happens, and why, but it still seems sort of magical. All that water contained in the air – a little like something into nothing. I love clouds too. Especially when viewed from above, because they look so solidly soft and inviting. I always find it difficult to believe that I would just plummet to a pancakey death, when it looks like I should be able to roll around in them…

But I digress. Evaporation and precipitation massively influence our planet’s climate, and temperatures. Water vapour is the most abundant greenhouse gas of all – I always assumed it was carbon dioxide. Clouds are a pretty efficient way to move all that water around. I also like to think of all the water that ever was just being shuffled around in different forms. A little like energy – it’s not created or destroyed, just changed.

So the experiment is almost over. I’m not sure how accurate my measurements have been – but I don’t think that’s the point. I think they want us to really think about experimental design, and observation, which I think I have done. I’ve enjoyed it, in a “back at school” kind of way. I’m already looking forward to the next one!

Blissful motion

For the first time in ages, I really enjoyed my journey to work this morning. I remembered why I love my motorbike. The freedom it engenders; the thrill and the beauty of the ride. It was much warmer and drier, and I flowed through bends and past imprisoned people half asleep in their boxes. It was just bliss.

Writing

I know some people who can write. I mean really write. They’re very good, and often very funny. I’m a little envious. Not too envious though – because they actually spend time doing it. I always think I want to, but never quite do. I have ideas, but don’t write them down (ha!) and I do my thinking on the bike, or somewhere equally unsuited to making notes. And my memory is pants.

I must do better. And I must do more reading!

Permalink 3 comments (latest comment by Vicky Fraser, Saturday, 15 Jan 2011, 13:16)
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Blue hair, yellow sweater, big smile

An inability to stop eating chocolate and Professor Brian Cox

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Edited by Vicky Fraser, Thursday, 17 Mar 2011, 09:24

This studying lark is bad. It’s bad. I never ate this much chocolate before. I think it’s a distraction technique to be honest. I sit down, there’s chocolate nearby, and it finds its way into my face. I don’t know how it does it. It may be of interest to science…

Speaking of science. I checked my precipitation gauges when I got home, and lo! there was 3mm of precipitation in each. The funnel had blown off, which I semi-predicted, but still. 3mm of shiny precipitation. And no pee. This is a Result. I dutifully recorded said measurement, stuck the funnel on with Blu-Tak and put them back outside. We’re forecast rain for the rest of my life, it seems, so I may actually get vaguely interesting results. Or at least different measurements.

I did have a little trouble measuring. I bent one of those metal tape measures at 10cm, so it starts from the bottom (if that makes sense), but I had trouble seeing the level. Would food colouring help perhaps? I’ll see. I might add some food colouring. Oh, and for my record, gauge 1 is the one without the funnel.

I’m blogging because Joe isn’t home yet. He’s on his way back from Leeds, but traffic is pants I think. So I can’t do an exercise vid, or yoga, because he has the computer and my yoga mat in the car. The blogging will turn into studying shortly. I finished chapter 2; chapter 3 is “The Earth’s Surface Temperature”. I’m hoping it’ll be a little more interesting…

Now. Last night we watched BBC’s Stargazing Live, which was great. I’m going to make a device to look at the sun on a piece of paper, and we saw great images of the eclipse that I missed because – again! – it was cloudy. But importantly, it was presented by Professor Brian Cox. I know he has a permanent smile, and he’s a little geeky. But there’s something about him. I want to cuddle him and keep him in my pocket. Ahem.

I do like him. He’s so obviously passionate about what he does. And passionate about introducing science to The Public too – and I guess why he’s always got that slightly knowing smile on his face. He’s got a job he loves, and he’s bloody lucky. And he knows it. It’s catching, too, that enthusiasm. I really hope that this course will take me somewhere near his plane of existence – in a slightly different direction, but really caring about what I’m doing.

This weekend I’m going to make that device for looking at the sun. And a pinhole camera. And win some poker money from my friends.

Interlude

A small rant. Sometimes I really enjoy my job. I like the people I share an office with, and the work is generally interesting enough to keep me from screaming. But why are some people SO BLOODY RUDE? One of my colleagues (from a different department) is just obnoxious sometimes, and there is no need for it. Drives me up the wall. One day he shall be told to go forth and multiply, but that day was not today.

Why are people rude though? And mean? I mean, everyone has an off-day, feels a little grumpy and out of sorts. But not everybody is bloody rude to other people. A little kindness goes a long way. A smile, a nice word, a greeting. No snapping, no shouting, no abruptness. It spreads the love, maaaan, and keeps the world spinning smoothly. A caravan of love, if you like. My resolution is to be nicer to people, especially the ones who are rude (not least because it really annoys them). Random acts of kindness, and smiling at strangers, is the way forward.

A new song

This morning I heard “I Want You” by Elvis Costello for the first time. I didn’t even realise I had it. It hit me like a hurricane; what a song. He drags you through the emotions with him whether you want to go there or not; it’s pleasure and pain, and it is stupendous.

It's here: http://www.youtube.com/watch?v=DWt6XxP2biE

Apparently I need the album “Blood and Chocolate” now – which is where the song is from. That sounds fine to me. More chocolate; but chocolate for the soul, this time.

Peace out.

Permalink 2 comments (latest comment by Vicky Fraser, Thursday, 13 Jan 2011, 19:10)
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Blue hair, yellow sweater, big smile

Precipitation and the art of teleportation

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I’m feeling pretty virtuous. Bank Holiday Monday, and I took down the Christmas decorations, performed an exercise video, filled the green bin with bits of unwanted garden, read and made notes (or actively read if you prefer) chapter two of Book 1 – Global Warming, and set up my precipitation gauges.

I changed my mind about the type of receptacle. I went for a couple of jam jars, but used the ex-Evian funnel in one of them. And, just to overcomplicate things, I’m going to set up two more in week two. With wax in the bottom, because I’m worried that the non-flat-bottoms will distort my results.

Yes, it’s probably not that important, but if I’m going to do the thing, I may as well do it properly. Anyway – I’ll post pictures in the next few days, and you can marvel at the positioning and sophisitication of my scientific techniques. And the messiness of my front garden. I’m hoping that my neighbours won’t have pee’d in it (more on that later).

Let’s all hope for some precipitation people. Ideally, that precipitation will come in the form of snow, but anything will do. I suspect I will rapidly lose interest if I keep going out into the cold to measure nothing.

So, a good and productive day, all in all. The book is a little slow to get going, to be honest. Every now and then there’s a box explaining what a pie chart is (for example). I’m a bit of a maths spaz, but even I’m okay with pie charts. They’re starting with basics, and so far I’m not feeling at all taxed.

Still, I’m studying again, and that makes me happy. Plus, the zombies haven’t arrived yet. This can only be A Good Thing. Particularly as we haven’t finalised the Zombie Plan yet…

Joe invited our neighbours around for mulled wine last night too. The mulled wine was yum; the neighbours entertaining, with their stories of flat-faced pigs and gigantic four-foot rabbits. Seriously, this thing’s a monster. I’ve only seen a photo, but that’s quite close enough.

He has a jet engine, which he’s promised to get going in the garden this summer. When we have a barbecue. Ha ha, I said. But no! He really does have a jet engine. Apparently it caused a bit of a ruction between him and another neighbour (not the one who likes to get naked and run around the front courtyard).

I reckon we should have a go at attaching it to a bicycle – it’ll sort out that big hill going into Radford Semele when we go to the pub. It’s a very big hill.

We chattered about this and that, and discovered that they like talking to strange people, which is grand – I also like talking to strange people, but I’m a little shy, so it’s nice to have someone to take the lead. We’ve vaguely planned a canoe trip around Anglesey. I think. I was talking about a couple of days with a tent on the Wye, but somehow we got onto sea kayaking and trips around entire islands. I’m not sure how I feel about this, but I’ll give almost anything a go.

So, gossip was gossiped, threats to pee in my experiment were declared, plans were made, and we were informed that we could, in fact, attend the residents’ association meetings. Which seem to be an excuse to drink wine and gossip. It’ll be a method of getting to know the neighbours better anyway, and that must be at least partly a good thing, right?

And so to bed. Which brings me on to the teleportation aspect of this entry. We had dispatched our smaller cat, Whiskey, to the living room just before retiring. Noodle was fast asleep on the sofa. (Noodle is our cow-print cat.) Lying in bed, having a read, trying to put off the horrible return to work after ten days off – and Whiskey appeared – just appeared – on the bed next to me.

I can only conclude that she has learned to teleport. She was very smug about it too. I’m intrigued as to what else she may be up to…

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