Liquid crystal (LC) is a state of matter whose properties are between those of conventional liquids and those of solid crystals. For example, a liquid crystal can flow like a liquid, but its molecules may be oriented in a common direction as in solid. There are many types of LC phases, which can be distinguished by their optical properties. The contrasting textures arise due to molecules within one area of material ("domain") being oriented in the same direction but different areas having different orientations. An LC material may not always be in an LC state of matter.
A thermometer is a device that measures temperature or temperature gradient. A thermometer has two important elements: (1) a temperature sensor in which some change occurs with a change in temperature; and (2) some means of converting this change into a numerical value. Thermometers are widely used in technology and industry to monitor processes, in meteorology, in medicine, and in scientific research.
In physics, a state of matter is one of the distinct forms in which matter can exist. Four states of matter are observable in everyday life: solid, liquid, gas, and plasma. Many intermediate states are known to exist, such as liquid crystal, and some states only exist under extreme conditions, such as Bose–Einstein condensates and Fermionic condensates, neutron-degenerate matter, and quark–gluon plasma. For a list of exotic states of matter, see the article List of states of matter.
Thermodynamic temperature is a quantity defined in thermodynamics as distinct from kinetic theory or statistical mechanics.
Differential scanning calorimetry (DSC) is a thermoanalytical technique in which the difference in the amount of heat required to increase the temperature of a sample and reference is measured as a function of temperature. Both the sample and reference are maintained at nearly the same temperature throughout the experiment. Generally, the temperature program for a DSC analysis is designed such that the sample holder temperature increases linearly as a function of time. The reference sample should have a well-defined heat capacity over the range of temperatures to be scanned. Additionally, the reference sample must be stable, of high purity, and must not experience much change across the temperature scan. Typically, reference standards have been metals such as indium, tin, bismuth, and lead, but other standards such as polyethylene and fatty acids have been proposed to study polymers and organic compounds, respectively.
Sintering or frittage is the process of compacting and forming a solid mass of material by pressure or heat without melting it to the point of liquefaction. Sintering happens as part of a manufacturing process used with metals, ceramics, plastics, and other materials. The nanoparticles in the sintered material diffuse across the boundaries of the particles, fusing the particles together and creating a solid piece.
Latent heat is energy released or absorbed, by a body or a thermodynamic system, during a constant-temperature process—usually a first-order phase transition, like melting or condensation.
A mood ring is a finger ring that contains a thermochromic element, or "mood stone", that changes colors based on the temperature of the finger of the wearer. Finger temperature, as long as the ambient temperature is relatively constant, is significantly determined by peripheral blood flow, which is modulated by the autonomic nervous system. A mood ring contains liquid crystals that change color depending on the temperature.
Smart glass, also known as switchable glass, dynamic glass, and smart-tinting glass, is a type of glass that can change its reflective properties to prevent sunlight and heat from entering a building and to also provide privacy. Smart glass for building aims to provide more energy-efficient buildings by reducing the amount of solar heat that passes through glass windows.
In chemistry, chromism is a process that induces a change, often reversible, in the colors of compounds. In most cases, chromism is based on a change in the electron states of molecules, especially the π- or d-electron state, so this phenomenon is induced by various external stimuli which can alter the electron density of substances. It is known that there are many natural compounds that have chromism, and many artificial compounds with specific chromism have been synthesized to date. It is usually synonymous with chromotropism, the (reversible) change in color of a substance due to the physical and chemical properties of its ambient surrounding medium, such as temperature and pressure, light, solvent, and presence of ions and electrons.
Crystallization is the process by which solid forms, where the atoms or molecules are highly organized into a structure known as a crystal. Some ways by which crystals form are precipitating from a solution, freezing, or more rarely deposition directly from a gas. Attributes of the resulting crystal depend largely on factors such as temperature, air pressure, and in the case of liquid crystals, time of fluid evaporation.
Thermal expansion is the tendency of matter to change its shape, area, volume, and density in response to a change in temperature, usually not including phase transitions.
Thermochromism is the property of substances to change color due to a change in temperature. A mood ring is an excellent example of this phenomenon, but thermochromism also has more practical uses, such as baby bottles which change to a different color when cool enough to drink, or kettles which change color when water is at or near boiling point. Thermochromism is one of several types of chromism.
Thermochromic ink is a type of dye that changes color when temperatures increase or decrease. It was first used in the 1970's within novelty toys like mood rings, but has found some practical uses in things such as thermometers, product packaging, pens. This ink has also found applications within the medical field for specific medical simulations in medical training. Thermochromic ink can also turn transparent when heat is applied; an example of this type of thermochromic ink is found on corners of an examination mark sheet. This proves that the sheet has not been edited or photocopied, and also on certain pizza boxes to show the temperature of the product.
A medical thermometer or clinical thermometer is a device used for measuring the body temperature of a human or other animal. The tip of the thermometer is inserted into the mouth under the tongue, under the armpit, into the rectum via the anus, into the ear, or on the forehead.
In chemistry, fractional crystallization is a stage-wise separation technique that relies on the liquid-solid phase change. It fractionates via differences in crystallization temperature and enables the purification of multi-component mixtures, as long as none of the constituents can act as solvents to the others. Due to the high selectivity of the solid - liquid equilibrium, very high purities can be achieved for the selected component.
An evaporator is a type of heat exchanger device that facilitates evaporation by utilizing conductive and convective heat transfer to provide the necessary thermal energy for phase transition from liquid to vapor. Within evaporators, a circulating liquid is exposed to an atmospheric or reduced pressure environment, causing it to boil at a lower temperature compared to normal atmospheric boiling.
Slurry ice is a phase changing refrigerant made up of millions of ice "micro-crystals" formed and suspended within a solution of water and a freezing point depressant. Some compounds used in the field are salt, ethylene glycol, propylene glycol, alcohols like isobutyl and ethanol, and sugars like sucrose and glucose. Slurry ice has greater heat absorption compared to single phase refrigerants like brine, because the melting enthalpy of the ice is also used.
Stripping is a physical separation process where one or more components are removed from a liquid stream by a vapor stream. In industrial applications the liquid and vapor streams can have co-current or countercurrent flows. Stripping is usually carried out in either a packed or trayed column.
