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RNA folding problem: Is it possible to accurately predict the secondary, tertiary and quaternary structure of a polyribonucleic acid sequence based on its sequence and environment? Protein design : Is it possible to design highly active enzymes de novo for any desired reaction?
List of unsolved problems may refer to several notable conjectures or open problems in various academic fields: Natural sciences, engineering and medicine [ edit ]
Freezing-point depression is a drop in the maximum temperature at which a substance freezes, caused when a smaller amount of another, non-volatile substance is added. Examples include adding salt into water (used in ice cream makers and for de-icing roads), alcohol in water, ethylene or propylene glycol in water (used in antifreeze in cars ...
Evaporation removes volatile liquids from non-volatile solutes, which cannot be done through filtration due to the small size of the substances. Liquid–liquid extraction removes an impurity or recovers a desired product by dissolving the crude material in a solvent in which other components of the feed material are soluble.
Total dissolved solids include both volatile and non-volatile solids. Volatile solids are ones that can easily go from a solid to a gaseous state. Non-volatile solids must be heated to a high temperature, typically 550 °C, in order to achieve this state change. Examples of non-volatile substances include salts and sugars. [3]
Non-methane volatile organic compounds (NMVOCs) are a set of organic compounds that are typically photochemically reactive in the atmosphere—marked by the exclusion of methane. [1] NMVOCs include a large variety of chemically different compounds, such as benzene , ethanol , formaldehyde , cyclohexane , 1,1,1-trichloroethane and acetone . [ 2 ]
Steam distillation is a separation process that consists of distilling water together with other volatile and non-volatile components. The steam from the boiling water carries the vapor of the volatiles to a condenser; both are cooled and return to the liquid or solid state, while the non-volatile residues remain behind in the boiling container.
Schematic diagram of the CVT process. Point A is the reaction between the starting materials and the transport agent to form volatile intermediates. These intermediates then are free to move around the inside of the tube via diffusion or convection (point B), and when they reach point C some of the gaseous species react to form solid products.