Developer Terms and Conditions › The Development › Molecular Sensing Models › A question for someone much smarter than myself..
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June 30, 2015 at 10:16 pm #1240
I know the chemical structure of a molecule that I am interested in measuring. Lets say water, h2o, because the chemical structure is known, can a series of wavelengths be calculated that should appear on the measurement when H2O is detected.
If so, I am assuming this could be used to define the hydrometry of a leaf. Otherwise I am not sure how that kind of measurement could be made.July 5, 2015 at 1:27 pm #1286HagaiKeymaster
While H2O is the pure chemical structure of water, in practice (in leaves and in general), water is never found in its pure H20 form and it typically interacts with other substances.July 8, 2015 at 10:33 pm #1296
With that information I would assume the testing procedure would be something like the following:
1) Weigh the leaf
2) Scan the leaf
3) Dehydrate the leaf
4) Weigh the leaf
The difference in weight would be it’s water content.
My issue would then be the need for a mathematical function (Before weight – After weight) to calculate the water content. This would be the real number to extrapolate from.
How do I do that with the current tools? Or am I getting ahead of things…July 9, 2015 at 6:35 pm #1297
I don’t think that you need a mathematical function.
One attribute of your leaf collection would be “% Hydration” and you would enter the calculated result there.
To make this easier, I would suggest a free text entry per sample with a reference (sample #1, sample #2, etc) so that you know which calculation belongs to which leaf.
Obviously you need lots of leaves with different starting hydrations.
You also need to be sure that your dehydration is only removing water.
regards, RogerJuly 13, 2015 at 8:24 am #1338HagaiKeymaster
Dehydrating leaves takes some skill, for example, defining the right dehydration temperature and length of dehydration.
Also, the temp of the leaf will significantly change the spectrum.
There is a variety of other things that have to be taken into consideration.
This isn’t too trivial and it’s a good example of the skill and knowledge that is required to build some of the models for SCiO.July 14, 2015 at 9:10 pm #1348
I am still not quite grasping things. Here is a sample testing procedure to illustrate my confusion.
1.) Store leaves in a controlled humid environment like a cigar humidor.
2.) Weigh the leaf sample,
3.) Create initial scan spectrum record (Before Rec) and write it to the DB.
4.) Using a low and tightly controlled temperature +- 1 deg airflow dehydrate the leaf for 5 min. Herbal vaporizers have this kind of control.
5.) Immediately scan the leaf after the test time expires (creating the After DB record for same test ) recording its temperature as well as the dehydrator air temperature
6.) Weigh the leaf to calculate the weight loss.
You have two spectrum scans (before/after) that theoretically can tell you the water content loss. So presumably the first scan has the starting content. But thats the real question to begin with, not the change. The leaf could be soaked in water for 24 hrs before the test to give a consistent starting point but it doesn’t get me any further to answering the question.
My question still remains about the math.. The before and after scans would need to be compared. I think I can do this in Excel by downloading the raw data and pairing up the before and after shots, but Im still looking at a change in water content, not the initial starting point.
My brain is now mush trying to visualize this problem.July 15, 2015 at 3:58 pm #1417
I think that the key to solve this is to dry as completely as possible, but with frequent intermediate weighing and associated scans.
Plotting the weights in a table will let you see when further weight loss has stopped, this will be close to zero % moisture as long as you are not cooking your sample.
– Now you can work back to estimate moisture at the earlier scans.
– Add this moisture content as an attribute measurement of each scan
– Try a Model to see if you get good results
Now try a fresh leaf, see what SCiO, predicts for moisture content, then measure the moisture by drying completely.
– If it is within a couple of percent – you are a winner! If not, more work is required.
Note 1: work on several leaves in parallel, scan each 5* at each stage. Don’t leave too much time between samplings to avoid biochemical changes. (Balance with rate of drying).
Note 2: you will need a very accurate balance, and good lab procedures (always weigh at a fixed temperature, avoid breezes etc).
Note 3: essential oils may evaporate also, keep dehydration temperatures gentle. Maybe estimate their quantity by washing a chopped leaf in ethanol (maybe ether?) dry both the washed leaf, and solvent to get base data. Repeat this for your slowly dried leaf. Remember to wash and dry a blank filter paper for comparison.
Note 4: A sachet of silica gel suspended near your leaf will help dehydration
Note 5: You could also scan a larger number of leaves and dry each completely, but the range of starting values may be too tightly clustered to get a reliable model.
Someone more skilled in lab practices or botany may laugh with scorn! Please feel free to criticise – I am not proud, and always ready to learn.
RogerJuly 20, 2015 at 2:13 pm #1502
Hi Redwingii – I think that this belongs here rather than projects.
I think that the salt and sugar scans for estimation need to respect physical state.
Dry salt and Dry sugar will scan very differently to solutions, because the molecular state has changed.
Note 1: The liquids were scanned in a white porcelain cup, I am still not sure about the best way for liquids.
Note 2: Liquids were intended to about 50% by weight, but not all the salt dissolved.
Attachments:You must be logged in to view attached files.August 20, 2015 at 10:41 pm #1779
I have been thinking about the data presented above. These are the basic ideas I think work somehow.
First.. The ripple for the solutions may be from the cup, not material interaction with water.
From the first graph we can see how much sugar bounces around compared to the salt, I think thats mostly due to O-H bonds in the chemical structures. Then both samples were dissolved in water. I see the second graph like the pure water (or cup bottom?) drags the spectrums of the sugar/salt toward the water spectrum. It looks to me like the salt solution follows the pure water spectrum much more than the sugar solution. I don’t have the data or mathematical confidence to see if we were to take the water/salt solution spectrum and subtract the water spectrum we would come up with the salt only spectrum. Don’t know, but intuitively it looks like that statement is true. Looking at the sugar/water solution spectrum compared to the sugar only, doesn’t feel as convincing but it still looks right to me.
I’m coming out with the idea that it will be possible to subtract one substance from another in some circumstances.
Not sure if I’m right, but thats what it looks like to me.
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