Proton-exchange membrane fuel cell
Proton-exchange membrane fuel cells (PEMFC), also known as polymer electrolyte membrane (PEM) fuel cells, are a type of fuel cell being developed mainly for transport applications, as well as for stat
Proton capture
Proton capture is a nuclear reaction in which an atomic nucleus and one or more protons collide and merge to form a heavier nucleus. Since protons have positive electric charge, they are repelled elec
Proton-exchange membrane
A proton-exchange membrane, or polymer-electrolyte membrane (PEM), is a semipermeable membrane generally made from ionomers and designed to conduct protons while acting as an electronic insulator and
Protonium
Protonium (symbol: Pn), also known as antiprotonic hydrogen, is a type of exotic atom in which a proton (symbol: p) and an antiproton (symbol: p) orbit each other. Since protonium is a bound system of
Nucleon magnetic moment
The nucleon magnetic moments are the intrinsic magnetic dipole moments of the proton and neutron, symbols μp and μn. Protons and neutrons, both nucleons, comprise the nucleus of atoms, and both nucleo
Proton nuclear magnetic resonance
Proton nuclear magnetic resonance (proton NMR, hydrogen-1 NMR, or 1H NMR) is the application of nuclear magnetic resonance in NMR spectroscopy with respect to hydrogen-1 nuclei within the molecules of
Eddington number
In astrophysics, the Eddington number, NEdd, is the number of protons in the observable universe. Eddington originally calculated it as about 1.57×1079; current estimates make it approximately 1080. T
Proton therapy
In medicine, proton therapy, or proton radiotherapy, is a type of particle therapy that uses a beam of protons to irradiate diseased tissue, most often to treat cancer. The chief advantage of proton t
Proton-coupled electron transfer
A Proton-coupled electron transfer (PCET) is a chemical reaction that involves the transfer of electrons and protons from one atom to another. The term was originally coined for single proton, single
Proton computed tomography
Proton computed tomography (pCT), or proton CT, is an imaging modality first proposed by Cormack in 1963 and initial experiment explorations identified several advantages over conventional X-ray CT (x
Proton-to-electron mass ratio
In physics, the proton-to-electron mass ratio, μ or β, is the rest mass of the proton (a baryon found in atoms) divided by that of the electron (a lepton found in atoms), a dimensionless quantity, nam
Proton–proton chain
The proton–proton chain, also commonly referred to as the p–p chain, is one of two known sets of nuclear fusion reactions by which stars convert hydrogen to helium. It dominates in stars with masses l
Proton spin crisis
The proton spin crisis (sometimes called the "proton spin puzzle") is a theoretical crisis precipitated by an experiment in 1987 which tried to determine the spin configuration of the proton. The expe
Proton radius puzzle
The proton radius puzzle is an unanswered problem in physics relating to the size of the proton. Historically the proton charge radius was measured by two independent methods, which converged to a val
Atomic nucleus
The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment
Hydron (chemistry)
In chemistry, a hydron is the general name for a cationic form of atomic hydrogen, represented with the symbol H+. The term "hydron", endorsed by the IUPAC, includes cations of hydrogen regardless of
Proton decay
In particle physics, proton decay is a hypothetical form of particle decay in which the proton decays into lighter subatomic particles, such as a neutral pion and a positron. The proton decay hypothes
Proton-transfer-reaction mass spectrometry
Proton-transfer-reaction mass spectrometry (PTR-MS) is an analytical chemistry technique that uses gas phase hydronium reagent ions which are produced in an ion source. PTR-MS is used for online monit
Protonophore
A protonophore, also known as a proton translocator, is an ionophore that moves protons across lipid bilayers or other type of membranes. This would otherwise not occur as protons cations (H+) have po
Proton
A proton is a stable subatomic particle, symbol p, H+, or 1H+ with a positive electric charge of +1 e elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an
Proton pump
A proton pump is an integral membrane protein pump that builds up a proton gradient across a biological membrane. Proton pumps catalyze the following reaction: H+[on one side of a biological membrane]
P-process
The term p-process (p for proton) is used in two ways in the scientific literature concerning the astrophysical origin of the elements (nucleosynthesis). Originally it referred to a proton capture pro
Rp-process
The rp-process (rapid proton capture process) consists of consecutive proton captures onto seed nuclei to produce heavier elements. It is a nucleosynthesis process and, along with the s-process and th
Proton emission
Proton emission (also known as proton radioactivity) is a rare type of radioactive decay in which a proton is ejected from a nucleus. Proton emission can occur from high-lying excited states in a nucl
Antiproton
The antiproton, p, (pronounced p-bar) is the antiparticle of the proton. Antiprotons are stable, but they are typically short-lived, since any collision with a proton will cause both particles to be a