All articles starting with P

p-Hydroxybenzaldehyde

p-Hydroxybenzaldehyde, also called 4-hydroxybenzaldehyde or 4-formylphenol, is a white crystalline aromatic aldehyde (C₇H₆O₂) made from phenol, used mainly as an intermediate for vanillin, flavors, fragrances, and pharmaceuticals.

Sep 19, 2026

P-MODEL

P-MODEL (ピー・モデル) is a Japanese electronic band formed in Tokyo in 1979 from the progressive group Mandrake, led by Susumu Hirasawa and central to Japan's technopop boom.

P-Phenylenediamine

P-Phenylenediamine (PPD), also known as P-diaminobenzene, is an aromatic diamine that is the primary intermediate in oxidative permanent hair dyes and a potent skin sensitizer.

p-polarization

P-polarization, also called TM polarization, is the state of light whose electric field oscillates entirely in the plane of incidence, and which is not reflected at all at Brewster's angle.

p-process

The p-process is the set of stellar nucleosynthesis mechanisms producing the rare proton-rich p-nuclei heavier than iron, mainly through the γ-process photodisintegration in core-collapse supernovae.

P-selectin glycoprotein ligand 1

PSGL-1 (CD162, Selplg) is a dimeric 120-kDa mucin-like leukocyte glycoprotein ligand for P-, E-, and L-selectin, requiring sialyl Lewis x O-glycan and sulfated N-terminal tyrosines for high-affinity P-selectin binding.

p-series

A p-series is an infinite series of the form 1 + 1/2^p + 1/3^p + ... with real exponent p, converging exactly when p > 1 and otherwise diverging.

P-site

The P-site (peptidyl site) is the ribosomal binding site for peptidyl-tRNA, the tRNA carrying the growing polypeptide chain; the initiator tRNA starts there each elongation cycle.

P-Square

P-Square, Nigerian Afrobeats/R&B duo of identical twins Peter and Paul Okoye from Jos, formed via the Smooth Criminals; albums Get Squared through Double Trouble; split 2017, reunited 2021, split again 2024; Mr P and Rudeboy now solo.

P-TEFb

P-TEFb (positive transcription elongation factor b) is the CDK9–cyclin T complex that releases paused RNA polymerase II into productive elongation; regulated by 7SK snRNP/HEXIM1, central to HIV Tat transactivation and a cancer drug target.

P-Toluenesulfonic acid

p-Toluenesulfonic acid, also called tosic acid or TsOH, is a strong aromatic sulfonic acid with a methyl group para to the sulfonic acid group, used as a catalyst in organic synthesis.

P-tuning

P-tuning is a parameter-efficient fine-tuning method for pretrained language models, introduced by Tsinghua University researchers in 2021, where trainable continuous prompt embeddings are optimized with a prompt encoder while the model stays frozen.

P-type ATPase

A P-type ATPase is a membrane protein that pumps ions across biological membranes using ATP, forming a phosphorylated intermediate that gives the family its name.

P-type conjugative transfer protein VirB9

P-type conjugative transfer protein VirB9, also called TraO or TrwF, is a roughly 300-residue periplasmic and outer-membrane component of bacterial type IV secretion systems, forming the VirB7-bound outer sheath of the core complex for conjugation and T-pilus biogenesis.

P-Valley

P-Valley (from Katori Hall's play Pussy Valley) is a Starz drama, premiered July 2020, set at The Pynk strip club in fictional Chucalissa, Mississippi, starring Nicco Annan, Brandee Evans, Shannon Thornton, and Elarica Johnson.

P-value

The p-value is the probability, assuming the null hypothesis is true, of a result at least as extreme as the observed one; small values are evidence against the null.

Sep 29, 2026

P-wave tomography

P-wave tomography is a seismic imaging method that inverts compressional wave travel times from millions of earthquakes to build 3-D models of P-wave velocity variations inside the Earth, from dense arrays to the whole mantle.

P-Xylene

P-Xylene, also known as para-xylene or p-xylol, is an aromatic hydrocarbon and one of the three xylene isomers, oxidized industrially to terephthalic acid for polyester fiber production.

P–n junction

A p–n junction is the interface between p-type and n-type regions of a semiconductor crystal, where a built-in electric field produces rectifying behavior in diodes, transistors, LEDs, and solar cells.

P. 5841

P. 5841 is an unnamed 5,841 m ultra-prominent peak in China, on the Salween–Yu Qu divide in northwest Yunnan and southeast Tibet, with no logged ascents.

Oct 10, 2026

P. A. P. Moran

P. A. P. Moran, full name Patrick Alfred Pierce Moran, was an Australian statistician who introduced Moran's I, the standard measure of spatial autocorrelation, in 1948.