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okay thank you uh yes i'll be

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discussing some results we've gotten

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from analyzing an archive set of samples

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that stanley muller produced in 1958

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where he used cyanamide which is a

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plausible prebiotic condensing agent to

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try to evaluate the polymerization of

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amino acids

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into larger molecules like peptides but

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before i do that i'll provide some

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context

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for this experiment so many of you are

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probably aware of the original military

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experiment that he published on in 1953

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where he used an apparatus

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like you see here on the left he put

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water in this small flask and he put the

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gases methane ammonia and hydrogen in

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this large flask over the course of

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seven days he sparked the experiment

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collected the samples and analyzed them

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with what was considered to be

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relatively state of the art technology

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in 1953 paper chromatography with

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hydrogen detection and what that did it

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produced these various spots here that

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all represent different compounds so in

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the case of his analyses they

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represented various amino acids so what

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this shows us

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is that you can simulate a

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possible early earth condition using

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very simple starting materials adding

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energy and you can form amino acids the

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building blocks for life

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but recently there's been some

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rejuvenated interest in some of the work

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that he did in the 1950s

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particularly with respect to a couple

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different experiments one of which was

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his volcanic experiment and that was one

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where he used an apparatus similar to

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the one you saw in the previous slide

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except it used an aspirator in it and

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what that did was it injected a jet of

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steam directly into the spark discharge

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simulating a volcanic eruption in the

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presence of lightning rich air on the

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early earth it's something that's common

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today and probably was common uh about

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3.8 billion years ago as well and what

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you can see from the analyses of these

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samples that he produced is that you get

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a great range and abundance of compounds

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that are produced by this experiment

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interestingly enough only a handful of

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these were actually detected by him when

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he first analyzed these samples himself

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but over five times as many can be

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detected today that speaks to the

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analytical achievements of uh

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of the past 60 years or so

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additionally there was his hydrogen

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sulfide experiment where he used a

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version of the classic apparatus and he

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used a reducing and oxidized gas mixture

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that included hydrogen sulfide and he

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sparked it for about three days let's go

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back sparked it for about three days and

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after he collected the samples he stored

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them in sealed sterilized vials but he

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never looked at them so this is the

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first analyses of these particular

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samples and you can see a chromatogram

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here on the top of the samples a

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chromatogram of the standards

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below that and even farther below that

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is this little line that's a

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it's an analysis of a procedural blank

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so it shows you that

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the sample handling processes

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contributed negative or negligibly

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excuse me to the presence of these amino

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acids that were detected in this sample

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set so it shows you that even by adding

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a simple gas like hydrogen sulfide

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you can have a huge uh effect on the

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range of products which included a

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number of sulfur bearing organic

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molecules like methionine which is

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important for eukaryotic protein

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synthesis

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but despite these

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various results that have been produced

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from these experiments detractors of the

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experiment would say you can take

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simulated early earth conditions and

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form amino acids but that doesn't mean

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that you formed life and that's

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absolutely true and in fact that gets

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that one of the biggest questions

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remaining in the field which is how do

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you go from these small monomer

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molecules like amino acids into these

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bigger molecules like ditri and

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polypeptides

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eventually working your way up into

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small proteins and one possible way to

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do that is through the use of condensing

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agents so these are simple molecules

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that are capable of facilitating

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polymerization of amino acids onto one

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another to form peptides

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and ideally what you could do is you

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could demonstrate

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a early earth condition and you would

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introduce a condensing agent and you

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would try to see if you can form both

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amino acids and dipeptides which would

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be their immediate polymerization

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product and show that in fact this

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process can happen under simulated early

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earth conditions

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so to give an overview of what would be

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a condensing agent there are a number of

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possible condensing agents that could

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have been readily

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excuse me readily formed on the early

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earth one of which would have been

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cyanomide uh also it's dimer

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diocyandiamide

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and then cyan cyanogen and carbonyl

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sulfide are also very plausible

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prebiotic condensing agents but for the

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purposes of this study we're going to

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focus on cyanomide and that leads us to

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his

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most recent set of archive samples that

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have been discovered and subsequently

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analyzed and that's his cyanomide spark

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discharge experiment so if you look here

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on the left you can see a photocopy of

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his original laboratory notebooks

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he was fortunately for us a very

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diligent notetaker and from this we can

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tell how he did the experiment

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we know that he took

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a version of the original apparatus and

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sparked the gases methane ammonia and

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water over the course of seven days and

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intermittently throughout the experiment

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he stopped the experiment three separate

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times to add cyanamide and it's worth

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noting that after the first edition of

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cyanomide he no longer heeded the

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apparatus

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and the reason for that is likely

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because of the risk of thermally

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decomposing the cyanomide if you

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thermally decompose your condensing

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agent you don't have a chemical

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mechanism or means by which to induce

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the polymerization of the amino acids

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you form so one thing we wanted to do is

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we wanted to look for not only the amino

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acids but also their immediate

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polymerization products dipeptides and

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diketopirazines or dkps which are the

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cyclic dipeptide and the reason why we

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want to look for those is because under

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equilibrium conditions all three of

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those would be predate

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present in a polymerization reaction so

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we took a targeted approach to look for

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amino acids and then a separate targeted

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approach to look for dipeptides and dkps

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so when we look for amino acids we use

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high performance liquor chromatography

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with fluorescence detection and triple

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quadruple mass spectrometry so the way

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this worked is we took our samples and

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we derivatized them so we prepared them

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for analysis with a chiral adduct known

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as othaldialdehyde and acetyl cysteine

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or opa nac for short

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and what this does is it tags primary

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amino groups and provides enantiomeric

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separation of amino acids with chiral

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centers so we take our samples and we

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push them through an hplc column

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as the compounds of interest get eluded

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off of the column they are either

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directed into the fluorescence detector

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for detection by one mechanism and

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they're also

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directed into the triple quad for mass

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and if we look at our amino acid data we

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can see very clearly that the cyanomide

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spark discharge experiment does produce

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amino acids and it produces them in good

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yields and in fact it compares very well

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to the previous spark discharge

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experiments that he had conducted

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what's worth noting is that you have the

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presence here of the amino butyric acids

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which are non-protein amino acids and

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you also have amino acids that are

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present in high abundance that have

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chiral centers they are racemic within

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experimental measures so that suggests

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to us the combination of the two factors

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suggests that these amino acids were

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formed within the experiment itself and

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were not a product of sample handling

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processes or other sources of

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terrestrial contamination

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now if we look at dipeptides and dkp's

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our approach for looking at these was to

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use ultra high performance liquid

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chromatography

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with

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quadrupole ion mobility separation and

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time-of-flight mass spectrometry so when

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your compounds of interest come off the

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column they come into the instrument

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here and they get ionized and that's

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when they go through ion mobility

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separation

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which separates the molecules based on

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their cross-sectional area when it

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interacts a drift gas acting in the

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opposite direction and then they enter

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into the mass spectrometer here for high

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resolution mass analysis

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and when we look at our dipeptide

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results we do see a lot of dipeptides

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and we see them in good yields as well

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and interestingly if you look at your

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amino acid to dipeptide ratio the ratio

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in the samples is about a thousand to

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one or a thousand to ten which agrees

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with experimental evidence that shows

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that at equilibrium conditions you

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should have amino acids in about a

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thousand times more abundant than your

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dipeptide so that suggests that these

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dipeptides were formed within the

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experiment and were not a product of

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contamination

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if you look at the structures down here

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at the bottom that shows you the type of

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chemical complexity that we're dealing

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with the kind the complexity that we're

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looking for we're not looking for super

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large macromolecules we're looking for

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something a little bit larger than amino

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acids

258
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so let's look at our dkps we do find

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dkps as well and this is very good

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evidence because it shows the full

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product of the polymerization of the

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amino acids so you see dkps in high

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abundance and when you compare your

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dipeptide to dkp abundance it's about

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one to ten or one to twenty which

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generally agrees with experimental

267
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evidence that shows that at equilibrium

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conditions your dipeptide dkp ratio

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should be about one to ten further

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suggesting that these dkps and these

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dipeptides were not a product of

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contamination

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so one question would remain from this

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type of study which is how does this

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happen what's the mechanism by which

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this might occur so to take a step in

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the direction of trying to address this

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question we're proposing a mechanism and

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it starts like this you have cyanomide

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and at equilibrium cyanomide would also

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be present as carbodynamide this

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carbodyamide can be protonated and then

283
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when protonated it can react with an

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amino acid like glycine in this case

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which would form the activated form of

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the amino acid so here would be

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activated glycine the activated form of

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the amino acid can then react with

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another amino acid to yield your

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dipeptide

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through two different means one of which

292
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would be a dehydration reaction the

293
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other one of which would be direct

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reaction with cyanomite itself to yield

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your dkp

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so from this study there's several

297
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things we can conclude first thing would

298
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be that this was the chronologically the

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first attempt to study condensing agents

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for their relevance to the origins of

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life additionally what we can conclude

302
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is that yes you can form simultaneously

303
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both amino acids and their

304
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polymerization products dipeptides and

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dkps under plausible simulated early

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earth conditions and that these

307
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condensing agents like cyanamide would

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provide us a chemical mechanism by which

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we can explain how this polymerization

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may take may have taken place on the

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early earth and this could have expanded

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upon and diversified the prebiotic

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chemical inventory from which life may

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have originated

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so with that i should acknowledge

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colleagues collaborators funding and

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this resource down here which provided

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us with access to stanley's lab

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notebooks so we can understand how he

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all right thank you very much do we have

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all right

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hi thanks for your talk i'm just

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wondering on these types of experiment

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right now what's the level of complexity

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we can achieve uh i know you were

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looking for a specific level complexity

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but how like long time chains can you uh

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synthesize abiotically in this type of

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experiment it's a good question so the

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question was uh what's the type of

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complexity that we can reasonably expect

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from these types of experiments and a

333
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lot of it depends on the variables that

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you introduce into the experiment what

335
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are your starting conditions how long do

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you let the experiment go on for so he

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would let the experiment run on average

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for a week if you let it run for

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probably two or three weeks you can

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generate even greater amounts of

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complexity and it also depends on

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subsequent compounds or components that

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you may introduce into the reaction

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apparatus so in this case he put a

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condensing agent if he continued to add

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more condensing agents maybe a greater

347
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variety of condensing agents that could

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have facilitated polymerization into uh

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polypeptides so one thing i didn't

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mention in this talk was we focused on

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dipeptides but we also did screen for

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tri

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and polypeptides and we did see

354
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tripeptides and

355
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very small polypeptides but we didn't

356
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quantitate that

357
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so you can reasonably expect

358
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polypeptides i'm confident in saying at

359
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this point and we're also in

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in the process of looking for things

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like nucleobases

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and moving on beyond just the simple

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monomer amino acids

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okay thanks very much eric yep i lied

365
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thanks for a great talk eric um i don't

366
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know much about condensing agents or

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cyanomide or other condensing agents

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things that you find in the natural

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environment and abundance is comparable

370
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to those that you or that stanley miller

371
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say that again

372
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are condensing agents like the ones that

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were used in this experiment or other

374
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condensing agents are those things that

375
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are commonly found in the environment

376
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and in concentrations comparable to

377
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those used here

378
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yes they are so these condensing agents

379
00:14:02,949 --> 00:14:00,720
that um that i discussed are readily

380
00:14:04,389 --> 00:14:02,959
formed under simulated early earth

381
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conditions so they're very simple

382
00:14:07,829 --> 00:14:06,160
molecules they're formed from the

383
00:14:10,150 --> 00:14:07,839
starting materials that were likely

384
00:14:11,910 --> 00:14:10,160
present on the early earth and using the

385
00:14:13,829 --> 00:14:11,920
energy sources that were likely present

386
00:14:16,230 --> 00:14:13,839
on the early earth like uv radiation so

387
00:14:18,389 --> 00:14:16,240
for example cyanamide is formed from the

388
00:14:20,870 --> 00:14:18,399
ultraviolet radiation of ammonium

389
00:14:22,470 --> 00:14:20,880
cyanide which is formed fairly readily

390
00:14:24,150 --> 00:14:22,480
on the early earth so these are very

391
00:14:26,710 --> 00:14:24,160
much plausible

392
00:14:28,790 --> 00:14:26,720
molecules and the concentrations he used

393
00:14:31,990 --> 00:14:28,800
in this experiment were on the order of

394
00:14:41,269 --> 00:14:32,000
millimolar to micromolar ranges which is

395
00:14:44,629 --> 00:14:42,790
it's a good question so we're looking

396
00:14:46,389 --> 00:14:44,639
for cyanamide in spark discharge

397
00:14:48,870 --> 00:14:46,399
experiments there's currently no

398
00:14:50,310 --> 00:14:48,880
literature that shows that cyanamide has

399
00:14:52,870 --> 00:14:50,320
been formed in spark discharge

400
00:14:55,189 --> 00:14:52,880
experiments one problem with that is a

401
00:14:57,110 --> 00:14:55,199
lot of the analytical instrumentation is

402
00:15:00,230 --> 00:14:57,120
mass spectrometry based so if you're

403
00:15:01,189 --> 00:15:00,240
looking for a really slow mass molecule

404
00:15:05,910 --> 00:15:01,199
in the

405
00:15:07,990 --> 00:15:05,920
tough to find it using mass spectrometry

406
00:15:10,310 --> 00:15:08,000
because there's certain mass cutoffs a

407
00:15:13,750 --> 00:15:10,320
lot of mass specs will not

408
00:15:17,590 --> 00:15:13,760
have very good accuracy or precision for

409
00:15:19,110 --> 00:15:17,600
masses below 50. so cyanamide is around

410
00:15:21,189 --> 00:15:19,120
42

411
00:15:22,629 --> 00:15:21,199
is their amu so it's difficult to look

412
00:15:24,550 --> 00:15:22,639
for that but you can use other things

413
00:15:25,910 --> 00:15:24,560
you can use chromatographic techniques

414
00:15:27,509 --> 00:15:25,920
but that's something that we're

415
00:15:29,189 --> 00:15:27,519
currently looking for is to see if it

416
00:15:31,910 --> 00:15:29,199
can be formed inherently within the