All articles starting with P
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Porosimetry
Porosimetry is a family of measurement techniques that determine the pore size distribution, porosity, and related characteristics of porous materials, most commonly by mercury intrusion or gas adsorption.
Porosity
Porosity is the fraction of a solid material's bulk volume made up of voids or pores rather than solid matter, a key property of rocks, ceramics, and catalysts.
Porous aromatic framework
A porous aromatic framework (PAF) is a porous organic polymer built from rigid aromatic units linked by carbon–carbon bonds, giving high surface areas and strong chemical stability.
Porous aromatic frameworks (PAFs) for CO2 capture
Porous aromatic frameworks (PAFs) are porous organic polymers built entirely from rigid carbon-carbon bonds between aromatic building blocks, first reported in 2009, used as adsorbents and membranes for capturing carbon dioxide.
Porous coordination cages
Porous coordination cages, also known as metal-organic cages or metal-organic polyhedra, are discrete molecular containers with permanent cavities, first reported by Makoto Fujita in 1990.
Porous ionic liquids for CO2 capture
Porous ionic liquids for CO2 capture are sorbent materials combining an ionic liquid with permanent porosity, so the flowing liquid contains permanent cavities that take up carbon dioxide.
Porous liquid
A porous liquid is a liquid with permanent porosity, proposed in 2007 and first realized in 2015 at Queen's University Belfast and the University of Liverpool.
Porous media model
A porous media model is a continuum approach representing fluid flow and solute transport through soils and rocks using averaged parameters like porosity and permeability.
Porous medium equation
The porous medium equation is a nonlinear degenerate parabolic equation, a modification of the heat equation that models gas flow in porous media with finite propagation speed.
Porous organic cages
A porous organic cage (POC) is a soluble cage-shaped organic molecule with an internal cavity; packed crystals form porous molecular solids used for gas separation.
Porous silicon anode
A porous silicon anode is a lithium-ion battery electrode made of silicon with internal pores that absorb the ~300% volume change of lithiation, enabling capacities far above graphite.
Porous silicon nanoparticles
Porous silicon nanoparticles (pSiNPs) are biodegradable silicon particles with tunable nanoscale pores, studied for targeted drug delivery, biosensing, and implant coatings; no clinical trials yet.
Porous spin-crossover frameworks
Porous spin-crossover frameworks are metal-organic frameworks, typically Hofmann-type iron(II) compounds, whose spin-state switching changes magnetism and color and couples to guest uptake in the pores.
Porphobilinogen
Porphobilinogen (PBG) is a pyrrole-containing dicarboxylic acid, formed from two aminolevulinic acid molecules, that builds heme and rises sharply in urine during acute porphyric attacks.
Porphobilinogen deaminase
Porphobilinogen deaminase, also called hydroxymethylbilane synthase (HMBS, hemC), is the third enzyme of heme biosynthesis, a cytosolic monomer with a dipyrromethane cofactor that polymerizes four porphobilinogen molecules into hydroxymethylbilane; deficiency causes acute intermittent porphyria.
Porphyria
Porphyrias are rare, usually inherited disorders of heme biosynthesis in which porphyrins or precursors build up in liver or bone marrow, causing acute neurovisceral attacks or sunlight-triggered skin disease; diagnosed biochemically via urine PBG or erythrocyte protoporphyrin.
Porphyria cutanea tarda
Porphyria cutanea tarda (PCT) is the most common porphyria, caused by hepatic UROD inhibition with iron overload, causing blistering photosensitivity; treated by phlebotomy or low-dose hydroxychloroquine.
Porphyria due to ALA dehydratase deficiency
Porphyria due to ALA dehydratase deficiency (ALAD porphyria, Doss porphyria, plumboporphyria): ultra-rare autosomal recessive acute hepatic porphyria, fewer than a dozen cases, elevated urinary ALA with normal PBG, ALAD gene 9q32.
Porphyria's Lover
"Porphyria's Lover" is a dramatic monologue by the English poet Robert Browning, first published in 1836, in which an unnamed speaker strangles his lover Porphyria with her own hair.
Porphyrin
Porphyrin (porphine, C20H14N4): aromatic tetrapyrrole macrocycle of four pyrrole rings joined by methine bridges; parent of heme, chlorophyll, and vitamin B12-type cofactors, used in photodynamic therapy.
Porphyrin-based metal–organic framework
A porphyrin-based metal–organic framework, also called a porphyrinic MOF or PMOF, is a crystalline porous solid using porphyrin linkers between metal nodes, applied in photocatalysis, sensing, and biomedical therapy.
Porphyrio
Porphyrio (Brisson, 1760) is the rail genus of swamphens and purple gallinules (Rallidae, Gruiformes), including the purple swamphen complex, the takahē, and the Gray-headed Swamphen established in Florida.
Porphyrio porphyrio
Porphyrio porphyrio, the purple swamphen (poule sultane; pukeko in New Zealand), is a large wetland rail of Europe, Africa, Asia, and Australasia, Least Concern, with 780,000 to 2,910,000 individuals and a disputed six-species split.
Porphyrites (mountain)
Mons Porphyrites (Gebel Abu Dokhan), Egyptian mountain in the Eastern Desert 50 km west of Hurghada; the ancient world's only source of imperial porphyry, quarried from AD 18 to the early fifth century and hauled to the Nile at Qena.
Porphyritic texture
Porphyritic texture is an igneous rock texture in which large crystals, called phenocrysts, sit in a distinctly finer-grained groundmass, classically formed by two stages of cooling.
Porphyromonas
Porphyromonas is a genus of anaerobic, gram-negative, pigmented rods in Bacteroidota, created in 1988 from Bacteroides species; type species P. asaccharolytica, best known for the periodontal pathogen P. gingivalis.
Porphyromonas gingivalis
Porphyromonas gingivalis, formerly Bacteroides gingivalis, is a Gram-negative anaerobic oral bacterium and keystone pathogen of chronic periodontitis; its gingipains, LPS, and outer membrane vesicles link it to systemic diseases, though human causal evidence remains limited.
Porphyromonas gingivalis fimbrillin protein
FimA (fimbrillin), encoded by fimA, is the 43-kDa structural subunit of Porphyromonas gingivalis major fimbriae; six genotypes (I, Ib, II, III, IV, V) differ in virulence, with types II and IV linked to periodontitis.
Porphyry (geology)
Porphyry is an igneous rock containing large crystals, called phenocrysts, set in a distinctly finer-grained groundmass; the name also denotes the purple imperial stone of Roman Egypt.
Porphyry copper deposit
A porphyry copper deposit is a large, low-grade copper ore body formed by hydrothermal fluids above shallow intrusions, supplying about 60 percent of world copper.