Trade involves the transfer of goods or services from one person or entity to another, often in exchange for money. A system or network that allows trade is called a market.
The product of mental labor — science — always stands far below its value, because the labor-time necessary to reproduce it has no relation at all to the labor-time required for its original production.
Karl Marx Addenda, "Relative and Absolute Surplus Value" in Economic Manuscripts (1861–63).
Cost and durability represent the main obstacles to full commercialisation of proton exchange membrane fuel cell (PEMFC) technology for vehicles. An EU-funded project is developing suitable materials for high-performance PEMFCs with a long lifetime.