I have encountered with a fascinating article! It is about tracking the evolution of viruses and how they make the other species sick by observing flora and chemical composition of oceans! Here is the most influential parts for me:
Tag: Chemistry
Excited electrons driving a reaction have been observed for the first time
“In past molecular movies, we have been able to see how atomic nuclei move during a chemical reaction,” said Peter Weber, a chemistry professor at Brown and senior author of the report. “But the chemical bonding itself, which is a result of the redistribution of electrons, was invisible. Now the door is open to watching the chemical bonds change during reactions.”
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Development of a small-scale helical surface dielectric barrier discharge for characterizing plasma-surface interfaces
Understanding plasma-surface interactions is important in a variety of emerging research areas, including sustainable energy, environmental remediation, medicine, and high-value
manufacturing. Plasma-based technologies in these applications utilize surface chemistry driven by species created in the plasma or at a plasma-surface interface. Here, we develop a helical dielectric barrier discharge (DBD) configuration to produce a small-scale plasma that can be implemented in a diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) cell and integrated with a commercial Fourier transform infrared (FTIR) spectrometer instrument to study plasma interactions with inert or catalytic solid media. The design utilizes the entire surface of a cylinder as its dielectric, enhancing the plasma contact area with a packed bed. In this study, we characterize the electrical and visual properties of the helical DBD design in an empty reaction cell and with added potassium bromide (KBr) powder packing material in both air and argon gas environments at ambient conditions. The new surface DBD configuration was integrated into a DRIFTS cell and the time evolution of water desorbing from the KBr packed bed was investigated. Measurements show that this configuration can be operated in filamentary or glow-like mode depending on the gas composition and the water content absorbed on KBr solid media. These results not only set the basis for the study of plasma-surface interactions using a commercial FTIR, but also show that controlling the gas environment and water content in a packed bed might be useful for studying different plasma regimes that are typically not possible at atmospheric pressure.
You can reach the paper via this link: Nazli Turan et al 2020 J. Phys. D: Appl. Phys
Underdetermination in Science
– Do you agree with Duhem that there cannot be crucial experiments? Can you make an example?
- I think there might be crucial experiments, but they do not guarantee the full description or explanation of a phenomenon. I want to give an example from my field of research (plasma catalysis). The catalytic reactions have been studied for years to increase the production rate of valuable products. Once we combine those reactions with some plasma applications, we observed an enhanced conversion of input gas flow (for example in the production of ammonia by nitrogen and hydrogen). Some thought plasma is affecting the catalytic materials, while the others believe the material is making some changes on plasma properties. Our group showed in the first experiment that there is no change in the macroscopic properties of plasma. Then, we designed an experiment with some expensive tools to see if there is any change on the catalytic material due to plasma. So, the second experiment seems so crucial to us to end the discussion on what is responsible for the enhancement. However, as I stated before, we didn’t probe the plasma in atomic level, it was a lumped study, which may cover the possible changes on plasma. In Duhem’s sense, there is no crucial experiments, but I believe an experiment might be still crucial, if its result will provide an answer to strengthen a possible explanation.
– In your opinion, what are the consequences for the rationality of science if we accept that theory choice does not work as an algorithm but it is influenced by values?
- As Kuhn suggested, the choices scientists rely on are affected by objective -shared- criteria as well as subjective factors. The algorithm is the part of objective process, mostly, because it returns a result based on predefined rules. However, this algorithm also requires some input to start with, which makes ‘the scientific algorithm’ shaky. The input information may come from the previous theories or experiments, that those are possibly influenced by the tradition or even ‘the spirit of the time’, if we think of geocentric theory as an example. On the other hand, science is still reliable and rational due to its testability and fallibility (yes, I love Popper). The geocentric theory was applicable to how stones fall, how water pumps function etc., but it required a stationary Earth. Many astronomers questioned this: “Ok, we observed other planets moving around, then why our lovely Earth is stationary?”. Because, they were not able to understand the role of gravity in a way that keeping the planets in their orbits and preventing people and atmosphere to fly away, till someone called Newton proved mathematically by inventing differential calculus. Is this theory testable, even though he just showed mystical mathematical expressions? Absolutely yes! Look around! You can easily see that ocean is moving back and forth at coasts due to tidal force between Earth and Moon, exactly how Newton describes. So, that is highly possible that theory choice is a combination of values and criteria, but once we accept that point of view, we’re also framing an unshakable stage for science itself and questioning its rationality is out of game, I guess.
Seminar notes: Is Hydrodynamics Relevant to the Origin of Life?
We are attending at least 8 seminars for every semester. Here is a short summary of the most interesting one!
This was an interesting talk mostly focused on the bubbles formed in ocean and relating those
with the origin of life. The speaker mentioned the mechanical forces created by waves in
ocean and pointed out that his group is solving a kind of hydrodynamics problem in a tube.
This tube can be any organic material can be found in ocean. They chose DNA nanotubes
because these are easy to obtain in lab. Then, they studied hydrodynamic shear on bursting
bubbles after breaking of the waves. His group measured and calculated shear and flow rate
inside DNA nanotubes in bubble foams and they found due to the high flow rates inside these
tubes, elongation of the tubes can cause fragmentation which can drive the production of new
molecules.
Speaker: Rizal Hariadi
I didn’t know graphene is so newly discovered!
Ok, it’s my ignorance. History time ! Year: 2004 Location: The University of Manchester Nobel Physics: 2010
Here is the whole story and information from ‘the home of graphene‘, Manchester.
Chemical bonds simulated with quantum computers!
“Quantum chemistry is the science of understanding the complicated bonds and reactions of molecules using quantum mechanics. The ‘moving parts’ of anything but the most-simple chemical processes are beyond the capacity of the biggest and fastest supercomputers. By modelling and understanding these processes using quantum computers, scientists expect to unlock lower-energy pathways for chemical reactions, allowing the design of new catalysts. This will have huge implications for industries, such as the production of fertilizers.”
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Surface-bound hydrogen: diffusion > desorption
Wait! What? “The first step in hydrogen storage is chemisorption, wherein gaseous H2 collides with Pd and adsorbs (sticks) to the surface. Secondly, the chemisorbed H atoms diffuse into the sub-surface, several nanometers deep.”
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Summary: SURFACE PROCESSES
In this part, surface adsorption-desorption reactions and secondary electron emission process are explained in detail. Surface processes have a key role on surface etching, for example. The gas phase on top of the surface interacts with the surface layer. Adsorption-desorption reactions affect gas-phase species concentration. Also, positive ion neutralization and secondary electron emission have effects on gas discharge. Therefore, gas and surface reactions are coupled.
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