17eugenekim
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Re: Help With Microbial Fuel Cell

Postby 17eugenekim » Sun Jan 09, 2022 5:04 pm

This is the air pump that keeps the environment anaerobic? I'm not too sure. If you're comparing electrical output between anaerobic and aerobic states (with/without pump), then I find it reasonable to find aerobic output higher than anaerobic output, because aerobic metabolism is more effective. Does that match what you're seeing? Also, is this different from what you observed in your previous experiments with MFCs?

As long as you're getting a nonzero reading with the MFC fully assembled, I think it makes sense from a theory standpoint. Wherever that nonzero reading settles, it becomes your control.

I'll think on it. In the meantime, if you have additional context, do let me know. Best of luck!

brindhaaa
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Re: Help With Microbial Fuel Cell

Postby brindhaaa » Tue Jan 11, 2022 10:35 am

Sorry for being unclear, but I meant the air pump that I inserted into the cathode, which is aerobic :). For my data section, another thing I want to analyze is also how much the air pump affects each MFC. I have readings every day that I have been taking for the past few weeks 3 times a day, and with and without an air pump. I expected readings to be much higher with the inclusion of an air pump in the cathode, but readings only increase by about 5-10 mV, and I am not sure why.

I am about 1-2 weeks from finishing my testing, and I am starting to begin to enter data into graphs and tables. I was thinking of running a T-test on my data to analyze its significance and credibility. Do you have any other suggestions as to what statistical tests I can do?

Thank you so much!

17eugenekim
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Re: Help With Microbial Fuel Cell

Postby 17eugenekim » Thu Jan 13, 2022 5:04 pm

I'm not too sure, either. Maybe there are obligate anaerobes contributing to the overall metabolism that are inhibited by air? Really not sure, sorry. An interesting question to look into, though, and at least mention in your results/conclusions!

How do you envision presenting your data? I don't know your exact methods for data collection, but still I can think of a few ways you could organize it. You could do line plots of each MFC with electrical readouts over time, showing confidence intervals around each timepoint. Also, because you have more than two groups, you may want to look into doing a one-way ANOVA. It's conceptually similar to a t-test but can do more than just pairs of datasets.

brindhaaa
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Re: Help With Microbial Fuel Cell

Postby brindhaaa » Mon Jan 17, 2022 5:43 pm

Hey!

I think it may be due to the fact that the air pump wasn't left in the water for too long before obtaining readings. But I will definitely make sure to implement this in my research paper!

Also, my results are looking fantastic! I have two more days left of testing (I tested for 3 weeks in total) and so far the 5% yogurt addition MFC has been peaking in results and surpassing both other MFCs. However, the 10% yogurt addition MFC began to increase in readings but at around day 12, rapidly began to decrease (I think this is due to the excess amount of lactate, which inhibited the enzymatic processes).

I have also finished graphing my results (besides for the two days that are left) and I noticed that the constant and 10% yogurt addition MFCs have been experiencing lots of fluctuation in readings. In other words, readings are rising then falling in a pattern. However, the 5% yogurt addition has been experiencing very little fluctuation. Do you think it would be accurate to say that in the 5% Yogurt MFC, anaerobic bacteria received a steady quantity of Lactobacillus and other probiotics, which led to a stabilization in anaerobic respiration levels?

One other thing I noticed is that in all three MFCs, my digital multimeter detected no readings on days 1 and 2, but suddenly detected a minimum of 100 mV starting from day 3. Do you know the reasoning behind this? I was researching a bit, and could it be due to the fact that the protons took some time to diffuse across the PEM for the circuit to close?

Finally (I apologize for the super long message :lol: ), I think I am going to go with the ANOVA test as you suggested. I discovered that there is such thing as a one-way and two-way ANOVA test...do you know which one would be best for my experiment? And also since I am doing an ANOVA test, I think I will scratch the t-test, since it is basically the same thing, just with fewer groups.

Thank you so much for all the help!
Brindha

17eugenekim
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Re: Help With Microbial Fuel Cell

Postby 17eugenekim » Wed Jan 19, 2022 7:20 am

Your data & initial analysis of it seems very interesting, and definitely headed in a good direction! It shows that you're very capable of thinking critically through the results of your experiment, so kudos! And glad the data collection hasn't been too frustrating.

I'm not sure what you mean by the 5% readings stability comment. To say it received a "steady quantity" confuses me, because the quantity of bacteria you added was always constant - you added 5% at the beginning. (Same goes for other groups, with different numbers.) Perhaps you meant something about the quantity of their metabolic products? Like there's an equilibrium of some kind regarding the outputs of Lactobacillus and the inputs of anaerobic respiration?

Remember that your current hypothesis centers around the activity of the LDH enzyme, which needs to turn pyruvate into lactate to free up electrons. Pyruvate is the product of simple glycolysis, which almost every cell can do as long as they have sugar. With that in mind, I'm actually wondering if the effect that you see on the 5% MFC is due to the added "fuel" - i.e. the sugar content of the yogurt - displacing the inhibitory effects of added lactate-making bacteria. I have no idea if that's correct, but what do you think? And what do you think you can say about the 10% MFC if we follow this line of reasoning?

I don't think this accounts for the fluctuation in your readings, by the way, which are also an interesting facet of your data. You said they have a cyclical pattern? How clear is it? I think we can keep throwing out ideas for why this is happening while we have the time. Also, from a presentation standpoint, you may want to call it something else, because "fluctuation" tends to imply less of a pattern in my experience.

As for ANOVA, one-way and two-way are what you'd expect from their names. Two-way ANOVA is what you do when you want to analyze how one variable is affected by two others (i.e. 2 independent variables, 1 dependent variable). It also assesses whether the effects of those two variables are independent from each other. I don't think you have 3 variables in your data, unless you want to do something with time. One-way is probably what you want for your hypothesis, but if there's more hypotheses you want to test, please go ahead and we can talk about the analysis required for that.


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