Helicity
Encyclopedia
The term helicity has several meanings. In physics
, all referring (perhaps obliquely) to a phenomenon that resembles a helix
. See:
In biochemistry
, helicity may also refer to the amount of alpha helix
represented in the secondary structure
of a protein
.
In chemistry
, helicity may refer to a type of planar chirality
.
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
, all referring (perhaps obliquely) to a phenomenon that resembles a helix
Helix
A helix is a type of smooth space curve, i.e. a curve in three-dimensional space. It has the property that the tangent line at any point makes a constant angle with a fixed line called the axis. Examples of helixes are coil springs and the handrails of spiral staircases. A "filled-in" helix – for...
. See:
- helicity (fluid mechanics)Helicity (fluid mechanics)In fluid mechanics, helicity is the extent to which helix-like motion occurs. If a parcel of fluid is moving, undergoing solid body motion rotating about an axis parallel to the direction of motion, it will have helicity...
, the extent to which corkscrew-like motion occurs - helicity (particle physics), the projection of the spin onto the direction of momentum
- magnetic helicityMagnetic helicityIn plasma physics, magnetic helicity is the extent to which a magnetic field "wraps around itself". It is a generalization of the topological concept of linking number to the differential quantities required to describe the magnetic field...
, the extent to which a magnetic field "wraps around itself" - circular dichroismCircular dichroismCircular dichroism refers to the differential absorption of left and right circularly polarized light. This phenomenon was discovered by Jean-Baptiste Biot, Augustin Fresnel, and Aimé Cotton in the first half of the 19th century. It is exhibited in the absorption bands of optically active chiral...
, the differential absorption of left and right circularly polarized light
In biochemistry
Biochemistry
Biochemistry, sometimes called biological chemistry, is the study of chemical processes in living organisms, including, but not limited to, living matter. Biochemistry governs all living organisms and living processes...
, helicity may also refer to the amount of alpha helix
Alpha helix
A common motif in the secondary structure of proteins, the alpha helix is a right-handed coiled or spiral conformation, in which every backbone N-H group donates a hydrogen bond to the backbone C=O group of the amino acid four residues earlier...
represented in the secondary structure
Secondary structure
In biochemistry and structural biology, secondary structure is the general three-dimensional form of local segments of biopolymers such as proteins and nucleic acids...
of a protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
.
In chemistry
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
, helicity may refer to a type of planar chirality
Planar chirality
Planar chirality is the special case of chirality for two dimensions.Most fundamentally, planar chirality is a mathematical term, finding use in chemistry, physics and related physical sciences, for example, in astronomy, optics and metamaterials...
.
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