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A chain-growth polymerization whose propagating active centres are free radicals. Initiation creates active chains, propagation adds monomers while regenerating an active centre, and termination or transfer changes the population of growing chains.[ref]
IUPAC Compendium of Chemical Terminology, fifth edition (Gold Book) by International Union of Pure and Applied Chemistry. radical polymerization, term R05075: radical kinetic-chain carriers
Chain growth by successive monomer coordination and migratory insertion at a metal-bound active site.
A functional centromere established at a location different from the ancestral centromere. Its formation can demonstrate that particular repeat arrays are not obligatory for centromeric function.
Propagation or re-establishment of a functional centromeric chromatin state across divisions without specification by a unique DNA sequence alone. Inheritance of chromosome function and invariance of the precise occupied base pairs are different claims.
Center of mass of a cone with a power-law radial density by 
Codex 0 Created 2026-10-20 Updated 2026-10-24
Codex 0 Created 2026-10-20 Updated 2026-10-24For a solid cone of base radius , height and density , take so the axis singularity, if present, is integrable. In cylindrical coordinates, at fixed radius the vertical range is . Integrating over height first givesThe first height moment is . Dividing proves . Thus uniform density has centroid , while density proportional to radius has centroid . For sums of such density components, total masses and first moments add, giving a mass-weighted centroid.
A receptor involved in embryonic patterning and immunity. In the early Drosophila melanogaster embryo, spatially restricted activation by Spätzle promotes nuclear Dorsal protein.
An inhibitory receptor on immune cells whose engagement can reduce activity during antigen stimulation. Blocking it does not replace missing antigen recognition or presentation.
A cyclin-dependent-kinase inhibitor induced in many p53-dependent arrest responses. Lower kinase activity helps restrain proliferation while stress is assessed.
A catalytic group that accepts a proton during a reaction step, increasing the reactivity of another group such as a hydroxyl nucleophile.
Transition state stabilization lowers an activation barrier when a catalytic environment stabilizes the reacting configuration more than the starting bound state. Stronger ground-state binding alone does not demonstrate catalysis.
General acid catalysis uses proton donation from an acid participating in the rate-influencing reaction pathway. It can activate an electrophile or assist protonation of a departing or newly formed group.
In acid catalysis, an acid accelerates a chemical reaction and is regenerated by the complete catalytic cycle. Protonating a substrate can create a better electrophile or leaving group, opening a lower-barrier pathway.
For example, acid-catalyzed ester hydrolysis begins by increasing the reactivity of a carbonyl group toward water. A catalyst changes the rates of forward and reverse reactions without changing their equilibrium constant. Specific acid catalysis depends on the solvent's protonated species, while general acid catalysis can involve other proton donors directly in the rate-controlling process.
Covalent catalysis creates a temporary covalent bond between catalyst and substrate, then breaks that bond while regenerating the catalyst. Merely forming a substrate–water bond does not constitute covalent catalysis by an enzyme residue.
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!
Intro to OurBigBook
. Source. We have two killer features:
- 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-calculusArticles 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/derivativeVideo 2. OurBigBook Web topics demo. Source. - 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.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
Figure 2. You can publish local OurBigBook lightweight markup files to either OurBigBook.com or as a static website.
Figure 3. Visual Studio Code extension installation.
Figure 5. . 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. 
- Infinitely deep tables of contents:
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact