Gas chromatography by Ciro Santilli 40 Updated 2025-07-16
This technique is crazy! It allows to both:
  • separate gaseous mixtures
  • identify gaseous compounds
You actually see discrete peaks at different minute counts on the other end.
It is based on how much the gas interacts with the column.
Detection is usually done burning the sample to ionize it when it comes out, and then you measure the current produced.
The procedure remind you a bit of gel electrophoresis, except that it is in gaseous phase.
Video 1.
Gas chromatography by Quick Biochemistry Basics (2019)
Source.
Video 2.
How I invented the electron capture detector interview with James Lovelock by Web of Stories (2001)
Source. He mentions how scientists had to make their own tools during the 40s/60s. Then how gas chromatography was invented at the National Institute for Medical Research and gained a Nobel Prize. Lovelock came in improving the detection part of things.
The name makes absolutely no sense in modern terms, as nor colors nor light are used directly in the measurements. It is purely historical.
A fuzzy control system is a type of control system that uses fuzzy logic instead of traditional binary sets (true/false or 1/0) to make decisions or control processes. Fuzzy logic is a form of many-valued logic that deals with reasoning that is approximate rather than fixed and exact. This makes it particularly useful for complex systems where uncertainty or imprecision is a factor.
Water by Ciro Santilli 40 Updated 2025-07-16
"Water" is the name for both:
Figure 2.
Ball-and-stick model of a water molecule
. Source.
Figure 3.
Simplified phase diagram of water
. Source. Note the triple point and critical point visible. Phase diagrams are so cool!
Figure 4.
Phase diagram of water
. Source. Note all the obscure phases of ice.
Ice by Ciro Santilli 40 Updated 2025-07-16
Ice is the name of one of the solid phases of water.
In informal contexts, it usually refers to the phase of ice observed in atmospheric pressure, Ice Ih.
Liquid helium by Ciro Santilli 40 Updated 2025-07-16
4 K. Enough for to make "low temperature superconductors" like regular metals superconducting, e.g. the superconducting temperature of aluminum if 1.2 K.
Contrast with liquid nitrogen, which is much cheaper but only goes to 77K.
Superfluid helium-3 by Ciro Santilli 40 Updated 2025-07-16
Surprisingly, it can also become a superfluid even though each atom is a fermion! This is because of Cooper pair formation, just like in superconductors, but the transition happens at lower temperatures than superfluid helium-4, which is a boson.
aps.org/publications/apsnews/202110/history.cfm: October 1972: Publication of Discovery of Superfluid Helium-3 contains comments on the seminal paper and a graph which we must steal.

Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
We have two killer features:
  1. topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
    Articles of different users are sorted by upvote within each article page. This feature is a bit like:
    • a Wikipedia where each user can have their own version of each article
    • a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
    This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
    Figure 1.
    Screenshot of the "Derivative" topic page
    . View it live at: ourbigbook.com/go/topic/derivative
  2. local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
    This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
    Figure 2.
    You can publish local OurBigBook lightweight markup files to either https://OurBigBook.com or as a static website
    .
    Figure 3.
    Visual Studio Code extension installation
    .
    Figure 4.
    Visual Studio Code extension tree navigation
    .
    Figure 5.
    Web editor
    . You can also edit articles on the Web editor without installing anything locally.
    Video 3.
    Edit locally and publish demo
    . Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
    Video 4.
    OurBigBook Visual Studio Code extension editing and navigation demo
    . Source.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
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