Apr 13

The impact of transition metal catalysts on macroscopic dielectric barrier discharge (DBD) characteristics in an ammonia synthesis plasma catalysis reactor

When non-equilibrium, low-temperature plasmas and catalysts interact, they can exhibit
synergistic behavior that enhances the chemical activity above what is possible with either process
alone. Unlike thermal catalysis, in plasma-assisted catalysis the non-equilibrium state of the
plasma produces reactive intermediates, such as excited species, that may play an important role
in the catalytic process. There are two primary plasma-surface mechanisms that could produce this
synergy: the effect of the plasma on the catalyst (e.g., enhanced adsorption / reaction of plasmaactivated
species, change of surface structure / morphology, hot spots, etc.) and the effect of the
catalyst on the plasma state. This work focuses on the latter. We use a laboratory-scale, packed
bed, dielectric barrier discharge (DBD) reactor to observe the influence of multiple alumina
(Al2O3) supported, transition metal ammonia (NH3) synthesis catalysts on the plasma electrical
and optical properties. We find that while the rates of ammonia synthesis over the materials
considered, including Fe/Al2O3, Ni/Al2O3, and Co/Al2O3, are different, the macroscopic
properties of the DBD are statistically indistinguishable. These results support the argument that
the observed synergy in our catalysis experiments is not due to the catalyst modifying the
characteristics of the plasma itself, but rather arises from differences in how the plasma
environment and plasma-generated species modify chemistry at the catalyst surface, although the
specific mechanism is still an outstanding question.

You can reach the paper via this link: Journal of Physics D: Applied PhysicsVolume 52Number 22

Francisco A Herrera1Gabriel H Brown1Patrick Barboun2Nazli Turan1Prateek Mehta2William F Schneider2Jason C Hicks2 and David B Go1,2

Published 22 March 2019 • © 2019 IOP Publishing Ltd

Apr 13

Balancing climate change with gender equality

Do we really care about both climate change and gender equality? If yes, please continue! If no, abort mission! World Resources Institute (WRI) has released comprehensive studies since 2016 showing that women’s access to decision-making process, low-carbon industry, infrastructure and transportation can boost energy efficiency, investments in renewable power, and reduction in carbon emissions.

Here is the report for women in power and utilities indicating the top 20 most gender-diverse energy utilities outperform less diverse ones (2015) although women are having less executive jobs all over the world. This graph is showing the percentage of women in strategic roles.

(image from the report)

(image from the report)

In this article, how to increase women’s participation to sustainable infrastructure and how they can affect low-carbon, sustainable development are discussed. At the end, there are three suggestions to enhance women’s participation and in turn, environmental outcomes and social benefits.

1. Level the playing field and facilitate skill-building.

2. Hire at all levels and across the supply-chain.

3. Foster an inclusive work environment.

(details in the article)

 

Lastly, the institute also released a guideline to create more diverse participation for panel discussions which are sometimes exhausting if you’re not in the privileged group. I will put some of the suggestions here:

1. Expand your network. We build panels from our existing networks, which often leads us to rely on
the same people, limiting the views and experiences expressed during a panel. Identify networks of
people typically underrepresented in your professional world and invest effort in developing
relationships with them. This may be a long-term endeavor, but this broader base of expertise and
perspectives can enhance future events, as well as projects.
2. Reach out. Once you have a concept for an event, reach beyond your immediate team to identify
speakers from this broader base, making it clear that you seek people with a particular technical
expertise who also bring varied perspectives in relation to the topics that are important to
represent.
3. As an organizer, commit yourself to improving your selection process. Do not put the responsibility
for engaging panelists from underrepresented groups on someone else from that group. Reach out
yourself, build a rapport with potential speakers and engage in a meaningful dialogue on the topic
to ensure that the invitation is genuine.
4. As a panelist, commit yourself to sharing the stage with a diverse panel. If you are invited to speak
on an externally-organized panel, ask the organizers who will be joining you. If you notice the panel
is homogenous, ask the organizers if they have considered including speakers from
underrepresented groups. Be prepared to offer suggestions on who the organizers could invite in
order to build a more diverse panel.
5. Mobilize resources and support. Speakers from underrepresented groups may face the issue of
underfunding. Set aside budget to ensure you are able to support their participation. In determining
the timing of your event, you may also want to check the availability of these speakers and adjust as
necessary to accommodate their participation. If you are organizing a longer event, such as a
conference or workshop, survey participants to understand what needs they may have, particularly
related to child care, to be able to attend and effectively engage.
6. Avoid tokenism. Invite speakers from a variety of relevant backgrounds. If only one member of an
underrepresented group is on the panel, avoid asking that person to speak for that group. Ask that
person to provide their insights and expertise on the subject being discussed. If you do want to ask
the person to ‘represent’ a particular perspective, prep the person for the question in advance and
preface the question with why and how it is relevant to the discussion. However, make every effort
to have a fully diverse panel so even a last minute drop out won’t leave you with a homogenous
group.

Adapted from:
https://hbr.org/2014/01/theres-no-excuse-for-all-white-male-panels/
How to avoid a gendered conference
https://netimpact.org/blog/6-steps-for-planning-a-diverse-conference

 

Dec 17

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 

Oct 21

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.

Scotch Tape

Sep 01

Science policy is giving rise to open science or a new form of capitalism?

Here is a provocative paper recently published. I will add my thoughts when I’m done with reading.

 

http://journals.sagepub.com/doi/abs/10.1177/0306312718772086

Aug 29

Notes from iPlasmaNano 2018

It was a really dense conference. Mostly, the professors gave talks about the latest updates of their research. The discussions were at high level. I tried to keep my eyes open to follow almost every talk 🙂 But, it’s worth it 🙂 Here are the topics attracting my attention.

 

 

Nano particle synthesis: https://scholar.google.com/citations?user=ni1mqkEAAAAJ&hl=en

–>in-situ FTIR:plasma-nano particle interaction

Graphite (anode–>mix with catalyst), BN nanotube synthesis by arc: https://scholar.google.com/citations?user=-PkzDBQAAAAJ&hl=en

–>B mix with metal (Ni, Co)

Computational plasma: http://faculty.ucmerced.edu/vayyaswamy/research.html

–>plasmaFOAM, Ti=Tg+((m_i/3k_b)mu_i^2E^2), non-Maxwellian ion number density 10^19 #/m^3

–>sheath oscillation: in low pressure-stochastic heating (can’t apply LFA,local field approx), in high pressure-ohmic heating

Space charge limited emission: https://aip.scitation.org/doi/10.1063/1.5004654

–>in high pressure-Matt-Gurney, in low pressure-Child-Langmuir, further Schrödinger

–>Rougher surfaces have lower breakdown voltage

Social impacthttps://www.linkedin.com/in/sung-jin-park-b2a5b510/

Plasma-surface interactions: https://www.researchgate.net/profile/Carles_Corbella

Hall thruster, BN self heating, catalyst with carbon nanotube: https://www.researchgate.net/profile/Carles_Corbella 

Tensile stress btw atoms, quantum dots with thermomechanical stresshttps://scholar.google.com/citations?user=wSJ6cxcAAAAJ&hl=en

–>larger atoms are collected in one dot

10kW, IEDF affects selectivity: https://scholar.google.com/citations?user=cRanOQUAAAAJ&hl=en

–>by lowering Q-factor under mismatch, more lossy matching –>e energy increases, equilvalent circuit mdelling by M.Kushner

Plasma-based tuning, lower resonance freq–sheath diminishes  https://scholar.google.com/citations?user=Qjw1ACoAAAAJ&hl=en

–>negative permittivity (meta material) — more number of electrons, conductivity increases

–>DC abnormal glow: i increases, res freq decreases

–>applied freq<< plasma freq (sqrt (e^2 n_e / m Epsilon_0))

–>alpha discharge –> walls are protected by ion bombardment

Double negative meta material (Epsilon<0, Mu<0): https://scholar.google.com/citations?user=LknRjyEAAAAJ&hl=en

–>1 W, low pressure, dielectric resonator

RF manipulationshttps://scholar.google.com/citations?user=PKxNAt0AAAAJ&hl=en

–>tuning number of electrons (n_e), Epsilon(V)=1-n_e/(w^2+v_m^2) where v_m^2=collision resonance freq which is a func of pressure

–>define ‘effective secondary emission coefficient’, i increases, cathode sheath diminishes for gamma mode of RF disch–>it is like DC with switching polarity (AC?)

–>P_noise / delta f = 4kT_e / (1+w^2/v_m^2) , power noise, in metal just  P_noise / delta f = 4kT_e but as noise reduces, conductivity decreases.

–>if purpose is to produce high number of electrons, HV, high pulsing rate –>low Te, high n_e

–>Add H2O vapor to reduce T_e

–>pd – 0.0001 Torr cm , field ionization, 20 ps ignition time (e time of flight) n_e – 10^10 cm^-3

CNT growth on substrates, energy storage applications, super capacitorhttps://scholar.google.com/citations?user=N2yMgt8AAAAJ&hl=en https://engineering.ucsb.edu/~mjgordon/research/index.html

In-situ plasma catalysishttps://www.research.manchester.ac.uk/portal/en/researchers/chris-hardacre(c10c2a33-9679-4501-b20f-272a2460b25c)/publications.html

–>NOx with HC, CO2 selectivity increased with Al2O3+Pd

–>Temp in plasma 100 C (?)

–>plasma jet in DRIFT, plastic dome,

–>EXAFS data

–>SEI: 2.637 kJ/L

Carbon arc dischargehttp://pdml.tamu.edu/

–>600 Torr, 2mm, e, He, C+, C*,C2…

–>55-60 A, low ablation-low deposit if anode diameter is decreased

–>T_e-1 eV

Laser produced plasma: http://www.inrs.ca/mohamed-chaker?f=publications

–>0.8 THz

–>VO2 for microsatellites

Jul 25

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.”

If you spend a little time with chemical reactions and bonds, you should notice that we’re just saying reactants turn into some products. The intermediate mechanism is tried to be explained by collision theory and density functional theory. There are many other interpretations in the literature, but there are millions of different possibilities for the reaction paths which are all simplified to understand the process. I wish I can comprehend more about quantum chemistry because after all, the microscopic behaviors are driving a reaction resulting in macroscopic properties. For now, simulations are valuable tool to observe the possible pathways and quantum computing is a promising approach for quantum chemistry.

World-first quantum computer simulation of chemical bonds using trapped ions

 

 

Jul 22

Acceleration with stars

His idea is that an advanced civilization could build a sphere that emits waste radiation in a specific direction. This radiation would accelerate the sphere—and the star it contains—in the opposite direction.”

I’m not sure about the process of building a sphere around ‘stars’, but the idea is very exciting. However, comparing the whole universe, how many stars should be covered with spheres? 100, 1000, 100000000 ?! I don’t think the only possibility to use this idea is just for the stars lost in the horizon. The expelled radiation can give enough thrust to spacecrafts, only if that radiation is collected and transmitted to the busters. Agh! We’re so little for the universe!

An advanced civilization could resist the accelerating expansion of the universe

 

Jul 19

Family tree :)

Here is my collage of powerpuffs with acrylic paints. This is a gift for my family 🙂 I’ve used this website: https://powerpuffyourself.com/#!/en

Jul 19

Stabilizing fusion plasmas

Sawtooth swings—up-and-down ripples found in everything from stock prices on Wall Street to ocean waves—occur periodically in the temperature and density of the plasma that fuels fusion reactions in doughnut-shaped facilities called tokamaks. These swings can sometimes combine with other instabilities in the plasma to produce a perfect storm that halts the reactions. However, some plasmas are free of sawtooth gyrations thanks to a mechanism that has long puzzled physicists.”

For the large scale fusion plasmas, it seems like a real challenge!

No more zigzags: Scientists uncover mechanism that stabilizes fusion plasmas

Older posts «