Kensei Kobayashi’s flow-reactor, the SCWFR, part 2

The SCWFR at Kensei Kobayashi's lab at Yokohama National University
The SCWFR at Kensei Kobayashi’s lab at Yokohama National University

Kensei Kobayashi’s group with the help of Takeo Kanaeko (a brilliant man) came up with another design where they named it Super Critical Water Flow Reactor (SCWFR) utilizing an infrared (IR) gold image furnace (Figure above). This enables the fluid in this system to heat up to 400 °C (or any desired temperature) within seconds (without pre-heating). This one specification is important as most autoclave and other flow reactors utilized an electrical heater which takes time to heat up to the desired temperature. This is undesirable as this “pre-heating” is also making the initial chemicals to react (or altered) to lower and rising temperature, which is not very realistic to a real vent. In other case, this is one of the slightly more realistic simulators i have worked to date.

Kobayashi’s ex-student, Nazrul Islam performed the survivability experiment using several amino acids (aspartic acid, threonine, serine, sarcosine, glutamic acid, α-aminobutyric acid, β- alanine, γ-aminobutyric acid, 5-aminovaleric acid and 6- aminohexanoic acid), 10 mM each) by heating them up at four different temperatures (250, 300, 350 and 400°C ) at 25 MPa for 2 min (that’s pretty fast). They showed that amino acids tend to show better recovery when it is hydrolyzed, suggesting some kind of aggregation and/or condensation is happening within the system. Additionally they also showed oligomerization of glycine (100mM) with the same temperature. At 400°C, no oligomerization was found. However, at 200-350°C, diketopiperazine, diglycine, triglycine and tetraglycine were formed. It was suggested that the glycine reactions in a supercritical fluid (300°C to 400°C) are quite different from those in the liquid phase (at 200–350°C). There were many other peaks of unknown compounds in all of the chromatograms of the unhydrolyzed products. Most of those peaks disappeared after acid hydrolysis. This particular findings however remains a mystery.

Another of Kensei’s sudent, Hironari Kurihara, used the SCWFR to test the stability of complex compounds produced from simulated primitive atmosphere (similar to Miller and Urey’s work). He then tested these compounds to assess the stability of some known amino acids. The complex-combined amino acids (from the primitive atmosphere simulation) preserved more amino acids (including amino acid precursors that give amino acids after acid hydrolysis) than free amino acids after heating in simulated SHS environments. In other words, these complex chemicals which could come from atmosphere (or space) could be better preserved if they are come into contact with the hot hydrothermal system which could have existed during the prebiotic-earth setting. This also hints that “clean or perfect” chemicals like amino acids used in many kinds of experiments are not necessarily showing the right picture when comes to chemical evolution on early earth. More on this in the future.

Many critics of hydrothermal vent simulators often argues that, simulators mentioned on this post and previous ones have a rather short flow-rate and short flow-length (showing low residence time, meaning how long the sample stays in the system). Critics usually cite studies that refer to residence time of fluids in axial hydrothermal environments range from years to decades, while those in lower temperature off-axis diffuse flow systems may be on the order of thousands of years. The problem with these studies about residential axial time of fluids is that, they’re are based on models and calculation only, no work has been done so far in regards to real time sampling or measuring the length of vent system (although, there are work in measuring the velocity of fluid emitting from a vent which looks promising for future measuring). Despite this limitation, i believe the future of simulators will be done using computer simulators, where experimental data from physical simulators (like the ones mentioned in this blog) could be used as parameters. The biggest advantage in this, is that, we do experiments on a larger scale which is could make the origin of life more complicated, interesting and not so straightforward, which I believe is a good problem to have in the future.

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Geological time scale part 2

Before starting the second part, i  would like to apologize for the delay. I was not super busy or anything, just being plain lazy without any excuses.

Moving on, When did life actually started? No one can actually tell. However scientists believe that life could have started or originated on multiple occasion and scenarios, only to be denied by major impacts. Despite this, it is speculated that life must have started around 3.8 billion years ago, when the LHB seized.

As mentioned in the previous post, the Archean period indicates, that earth has more water and minerals to make life plausible but, before that the atmosphere and the ocean has to form and cool off from HLB impacts. Only after this events, life could kick-start. Prebiotic chemistry happened during this time where the formation of lipids and peptides aggregates were formed. The idea of a “prebiotic soup” also must have happened here too. Many models were designed to imitate this period as well.

The protocell or LUCA (last universal common ancestor); could have emerged right after the prebiotic chemistry has taken place with metabolic diversification (which is about 3.8 -2.5 billion years ago). However, these are all scientific hypothesis, there are no fossilized records what so ever. Overall the origin of life idea is based on several hypothesis to build the prebiotic world and it’s chemistry. This grey area is where many chemical astrobiologist (like me) are focusing on. The idea however, is heavily supported by present knowledge of chemistry and geology with the power of models.

The earliest Stromatolites which is considered as the earliest micro fossils we have, is hypothesized (with heavy dispute) to have occurred right after this . The cyanobacteria rose with the power of photosynthesis giving an influx of oxygen to earth’s atmosphere, the very reason we have oxygen now. However, it should be noted that oxygen is toxic, meaning that other life forms utilizing non- oxygen metabolism during that time, must have went extinct without evidence. The Proterozoic eon starts here. The Cambrian explosion also starts here with the increasing of oxygen, leading to life forms which were well fossilized such as Opabinia and Marrella. Watch the video above to see how these creatures look like.

There are plenty of scientific evidence here. I will not be elaborating further on what happened after this. Many studies have been done, it is an establish science. We pretty much know what happened after the Cambrian explosion, but not what happened before that.

That’s all for now. The next post is about the possible sites of life’s origin.

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