PPI

PPI may refer to:

Biochemistry

PP_i, the anion P₂O₇⁴⁻, a pyrophosphate

PPI, peptidylprolyl isomerase a human chaperone protein also known as Prolyl isomerase

PPI, a right-handed form of polyproline helix, a secondary structure in proteins

PPI, Protein–protein interaction frequently referring specifically to the network of interactions between a subset of proteins in a living cell.

Indicators and indexes

Pareto priority index, an index to prioritize projects

Plan position indicator, a display of tactical information from RADAR or other sources.

Producer Price Index, a metric used in economics, related to inflation

Insurance

Payment protection insurance

Linguistics

Positive polarity item

Media

Pakistan Press International

Medicine

Patient package insert, a document included with certain prescription medications

Prepulse inhibition, the ability of the nervous system to attenuate the startle response when a warning stimulus is given

Proton-pump inhibitor, a drug that reduces gastric acid secretion in the stomach

Loading... please wait...

This page contains text from Wikipedia, the Free Encyclopedia - https://wn.com/PPI

Dots per inch

Dots per inch (DPI, or dpi) is a measure of spatial printing or video dot density, in particular the number of individual dots that can be placed in a line within the span of 1 inch (2.54 cm).

Monitors do not have dots, but do have pixels; the closely related concept for monitors and images is pixels per inch or PPI. Many resources, including the Android developer guide, will use the term DPI interchangeably with PPI, however.

DPI measurement in monitor resolution in pixels

Old CRT type video displays were almost universally rated in dot pitch, which refers to the spacing between the sub-pixel red, green and blue dots which made up the pixels themselves. Monitor manufacturers used the term "dot trio pitch", the measurement of the distance between the centers of adjacent groups of three dots/rectangles/squares on the CRT screen. Monitors commonly used dot pitches of 0.39, 0.33, 0.32, 0.29, 0.27, 0.25, or 0.22 millimetres [mm] (0.0087 in).

LCD monitors have a trio of sub pixels, which are more easily measured.

Pyrophosphate

In chemistry, pyrophosphate is a phosphorus oxyanion. Compounds such as salts and esters are also called pyrophosphates. The group is also called diphosphate or dipolyphosphate, although this should not be confused with two phosphates. As a food additive, diphosphates are known as E450. A number of hydrogen pyrophosphates also exist, such as Na₂H₂P₂O₇, as well as the normal pyrophosphates.

Chemistry

Pyrophosphates were originally prepared by heating phosphates (pyro from the Greek, meaning "fire"). They generally exhibit the highest solubilities among the phosphates; moreover, they are good complexing agents for metal ions (such as calcium and many transition metals) and have many uses in industrial chemistry. Pyrophosphate is the first member of an entire series of polyphosphates.

The term pyrophosphate is also the name of esters formed by the condensation of a phosphorylated biological compound with inorganic phosphate, as for dimethylallyl pyrophosphate. This bond is also referred to as a high-energy phosphate bond.

PPI