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Protective stop
A protective stop is an automatic stop of a machine or robot triggered by a safety device such as a light curtain or scanner, defined in ISO 10218-1.
Protein Data Bank
The Protein Data Bank (PDB) is the open-access archive of experimentally determined 3D structures of proteins and other biological macromolecules, established in 1971 at Brookhaven National Laboratory.
Protein Information Resource
The Protein Information Resource (PIR) is a public bioinformatics resource that collects and annotates protein sequence information, established in 1984 and a founding partner of UniProt since 2002.
Protein language model
A protein language model is a neural network, typically a Transformer, trained on large protein sequence databases to predict structure, function, and design in computational biology.
Protein refolding
Protein refolding converts unfolded or aggregated proteins, typically recovered from E. coli inclusion bodies, back into their native three-dimensional structure, a key and costly step in biopharmaceutical manufacturing.
Protein-sucrose
Protein-sucrose is a food ingredient of sucrose blended with food-grade protein, developed by the Israeli company Incredo to make sugar taste sweeter so less is needed.
Proterra
Proterra was an American electric vehicle technology company founded in 2004 and headquartered in Burlingame, California, that sold around 1,200 electric transit buses before filing for bankruptcy in August 2023.
Protests against SOPA and PIPA
The protests against SOPA and PIPA were online activism in late 2011 and January 2012 against two US anti-piracy bills, culminating in the January 18, 2012 Internet blackout.
ProtGPT2
ProtGPT2 is a GPT-2-style language model that generates novel protein sequences, trained on 50 million UniRef50 sequences and released in 2022 by Noelia Ferruz and colleagues at the University of Bayreuth.
Proto (tools)
Proto is an American brand of industrial hand tools, torque instruments, and tool storage, owned by Stanley Black & Decker and sold through industrial distributors for maintenance work.
Protoclone
Protoclone (Protoclone V1) is a full-body humanoid robot prototype by Clone Robotics, using over 1,000 water-driven artificial muscles on a 3D-printed skeleton, shown twitching in a viral 2025 video.
Protocol Buffers
Protocol Buffers, also known as Protobuf, is a language-neutral, schema-driven binary serialization system developed at Google and released in 2008, and it defines the message format used by gRPC.
Protocol data unit
A protocol data unit (PDU) is the unit of data exchanged between peer protocol entities in one layer of a network stack, with layer-specific names like segment, datagram, and frame.
Protocol of 2005 to the Convention for the Suppression of Unlawful Acts Against the Safety of Maritime Navigation
The Protocol of 2005 to the Convention for the Suppression of Unlawful Acts Against the Safety of Maritime Navigation is a multilateral treaty adopted in London in 2005.
Protocol stack
A protocol stack, also called a network protocol stack, is a layered set of communication protocols in which each layer provides services to the layer above it, as in TCP/IP.
Protocol-Independent Multicast
Protocol-Independent Multicast (PIM) is a family of IP multicast routing protocols that builds multicast trees using unicast routing information without depending on any specific unicast routing protocol.
Protolabs
Protolabs is an American digital manufacturing service, founded in Minnesota in 1999 by Larry Lukis, that makes custom prototypes and low-volume parts from uploaded 3D CAD models.
Proton (software)
Proton, also known as Valve Proton or Steam Proton, is Valve's open-source compatibility tool, released in 2018, that runs Windows games unmodified on Linux through Steam, including the Steam Deck.
Proton exchange membrane water electrolysis
Proton exchange membrane water electrolysis (PEM electrolysis) is an electrochemical method of splitting water into hydrogen and oxygen with a solid polymer membrane as the electrolyte, operating at about 70–90 °C.
Proton Holdings
Proton Holdings Berhad, incorporated in 1983 as Perusahaan Otomobil Nasional, is Malaysia's national automotive manufacturer, known for the Proton Saga and majority-owned by DRB-HICOM and Geely.
Proton Pass
Proton Pass is an end-to-end encrypted password and identity manager developed by Proton AG, the Swiss company behind Proton Mail, which launched in 2023 and also generates hide-my-email aliases.
Proton Saga
The Proton Saga is a compact sedan produced by Malaysian carmaker PROTON since 1985, when it launched as Malaysia's first national car, based on the Mitsubishi Lancer Fiore.
Proton Satria
The Proton Satria was a three-door hatchback made by Malaysian carmaker Proton: a Mitsubishi Mirage-based model from 1994 to 2005, then the in-house Satria Neo.
Proton Wira
The Proton Wira, known as the Proton Persona in the United Kingdom, is a Malaysian compact sedan and hatchback based on the Mitsubishi Lancer, produced from 1993 to 2009 with over 950,000 units sold.
Proton-conducting solid oxide electrolysis cells
Proton-conducting solid oxide electrolysis cells (PCECs), also called protonic ceramic electrolysis cells or P-SOECs, are electrochemical devices that split steam into pure hydrogen at intermediate temperatures of roughly 400–700 °C.
Proton-exchange membrane fuel cell
A proton-exchange membrane fuel cell (PEMFC) is an electrochemical device that converts hydrogen and oxygen into electricity through a thin polymer membrane, powering most small stationary fuel cells by count.
Proton-K
The Proton-K (Протон-К, GRAU 8K82K) was a Soviet, later Russian, heavy-lift carrier rocket built by Khrunichev, flown from 1967 into the 2000s and now retired.
Proton-M (Протон-М)
Proton-M, also known as Протон-М, is an expendable Russian heavy-lift launch vehicle, first flown in 2001 from Baikonur and built by the Khrunichev Space Center.
Protonic synaptic transistor
A protonic synaptic transistor is a three-terminal device in which protons migrating through an electrolyte gate a semiconductor channel, mimicking synaptic functions like long-term potentiation.
Prototype
A prototype is an early, tangible version of a product or system built to test ideas, expose flaws, and gather feedback before committing to full-scale production or development.