Topics (384k) Articles (398k) Users (410) Discussions (242) Comments (383) Files (13k) New article
A boundary between crystalline regions or phases. Its excess free energy depends on orientation, chemical bonding and lattice matching.
A one-atom close-packed structure with a face-centered cubic lattice and close-packed stacking sequence.
A position surrounded by four nearest sites at tetrahedron vertices. A conventional face-centred cubic cell has eight such sites, at all combinations of quarter and three-quarter fractional coordinates. Whether occupancy constitutes a defect depends on the reference crystal.
For basal vectors of equal length separated by120degrees and perpendicular height , cell volume is . A full hexagonal prism drawn around it has three times this volume and must contain three times as many atoms if used for density calculations.
Camouflage is concealment that reduces the chance that an observer detects or recognizes an organism. Crypsis can work through resemblance to the background; other patterns can disrupt the apparent outline of a body. Their effectiveness depends on the observer's sensory system, viewing conditions and animal behaviour.
A useful test measures detection or attack by the relevant predator against several backgrounds. A colour match judged by a human does not establish the same match for an observer with different colour vision. Camouflage and resemblance to a defended model in Batesian mimicry therefore require different explanations.
Sequencing-based mapping after crosslinking and immunoprecipitation. Stabilizing RNA–protein contacts before isolation can improve positional evidence, while crosslinking and recovery biases affect which interactions are observed.
Time-dependent strain under load that is enhanced or driven by irradiation-produced defects. Stress changes defect capture and dislocation motion; the dependence need not match ordinary thermal creep.
Relative tangential motion of neighbouring crystal grains along their boundary, requiring accommodation to avoid incompatibility and damage. It can contribute to high-temperature creep.
nucleation and growth of cavities on grain boundaries under high-temperature stress. Coalescence can cause creep rupture. This is distinct from vapour-bubble formation in a liquid.
The absolute temperature divided by an appropriate melting temperature, . It is a useful scale for comparing thermally activated deformation; Celsius temperatures cannot be used directly in the ratio.
A regime in which the steady material creep rate varies approximately as a power of stress, , with thermally activated coefficients. In ordinary dislocation-creep fields, glide, climb and recovery give an exponent greater than the linear-stress diffusion-creep limit.
Permanent shape change driven by stress-biased atomic or vacancy diffusion. Different chemical potentials at differently stressed grain surfaces drive material transfer, requiring grain-shape accommodation. Bulk and boundary transport give different grain-size dependencies.
The approximately constant strain rate in secondary material creep at specified stress, temperature and material state. A lifetime estimate assumes that rate remains representative; evolving area, damage and tertiary material creep can shorten it.
Water weakening of rocks denotes the reduction of mechanical strength or increase of material creep rate produced by water or hydrogen-related defects under specified conditions. The effect depends on mineralogy, water activity, temperature and deformation mechanism; atmospheric dryness alone does not measure a planet's interior water content.
Dislocation creep is time-dependent crystal deformation through motion and interactions of dislocations. A common constitutive model is with , giving stress-dependent effective viscosity. Unlike diffusion creep, it often has weak grain-size dependence over the regime being modelled.
A deformation mechanism map shows which deformation process dominates in a specified range of stress, homologous temperature and other controlled variables. Boundaries shift with grain size, composition, pressure, water content and the constitutive laws; they are not universal lines determined by homologous temperature alone.
A double bond is a covalent bond of bond order two. Restricted rotation and substituent geometry at a carbon–carbon double bond can affect acyl-chain packing in a lipid bilayer.
A glycosidic bond links a sugar to another group through its anomeric centre. In a nucleotide, rotation about the base–sugar linkage contributes to anti and syn conformations; it is distinct from the phosphate links joining successive nucleotides.
A covalent bond with bonding electron density of cylindrical symmetry around the internuclear axis; end-on orbital overlap is a common localized construction.
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