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In chemistry, a precursor is a compound that participates in a chemical reaction that produces another compound. In biochemistry , the term "precursor" often refers more specifically to a chemical compound preceding another in a metabolic pathway , such as a protein precursor .
An artificial membrane, also called a synthetic membrane, is a membrane prepared for separation tasks in laboratory and industry. Atmospheric pressure Atmospheric pressure is the pressure at any given point in the Earth's atmosphere. Atom The atom is the smallest unit of an element that retains the chemical properties of that element.
The proton-exchange membrane is commonly made of materials such as perfluorosulfonic acid (PFSA, sold commercially as Nafion and Aquivion), which minimize gas crossover and short circuiting of the fuel cell. A disadvantage of fluor containing polymers is the fact that during production (and disposal) PFAS products are formed.
Syngas, or synthesis gas, is a mixture of hydrogen and carbon monoxide, [1] in various ratios. The gas often contains some carbon dioxide and methane . It is principally used for producing ammonia or methanol .
A protocell is a pre-cell in abiogenesis, and was a contained system consisting of simple biologically relevant molecules like ribozymes, and encapsulated in a simple membrane structure – isolating the entity from the environment and other individuals – thought to consist of simple fatty acids, mineral structures, or rock-pore structures.
Gasoline can be released into the Earth's environment as an uncombusted liquid fuel, as a flammable liquid, or as a vapor by way of leakages occurring during its production, handling, transport and delivery. [90] Gasoline contains known carcinogens, [91] [92] [93] and gasoline exhaust is a health risk. [82]
Fuel gas is contrasted with liquid fuels and solid fuels, although some fuel gases are liquefied for storage or transport (for example, autogas and liquified petroleum gas). While their gaseous nature has advantages, avoiding the difficulty of transporting solid fuel and the dangers of spillage inherent in liquid fuels, it also has limitations.
Gas exchange is the physical process by which gases move passively by diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liquid, a gas-permeable membrane, or a biological membrane that forms the boundary between an organism and its extracellular environment.