crystallography

Biophysical techniques are methods used for gaining information about biological systems on an atomic or molecular level. They overlap with methods from other branches of science. Main biophysical techniques are: Spectrophotometry, the measurement of the transmission of light through different solutions or substances at different wavelengths of light. Colorimetry is an example of this. Circular dichroism, a method for detecting chiral groups in molecules, especially to determine the secondary structure of ...

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In crystallography, the cubic crystal system (or isometric crystal system) is the most symmetric of the 7 crystal systems. The system is composed of the three Bravais lattices whose symmetry group is that of a cube. The three Bravais lattices that form the cubic crystal system are: The cubes drawn are the conventional unit cells. For a cube whose vertices include 000 and 200, bcc has additional lattice point 111, while fcc has 110, 101, and 011. For bcc the primitive cells have a volume of 1/2 of the cube, e.g. th ...

Including:

• Cubic crystal system - Halite structure

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Ammolite is a rare and valuable opal-like organic gemstone found primarily along the eastern slopes of the Rocky Mountains of the United States and Canada. It is made of the fossilized shells of ammonites, which in turn are composed primarily of aragonite, the same mineral that makes up nacreous pearls. It is one of the three biogenic gemstones, the other two being amber and pearl.1 In 1981, ammolite was given official gemstone status by the World Jewellery Confederation, the same year commercial mining of ammolite began. In 2004 it was designated th ...

Including:

• Ammolite - Properties
• Ammolite - Formation occurrence and extraction
• Ammolite - Gemstone quality
• Ammolite - Treatments
• Ammolite - Imitations
• Ammolite - Use in jewelry
• Ammolite - Notes

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X-ray or Röntgen radiation is a form of electromagnetic radiation with a wavelength in the range of 10 nanometers to 100 picometers (corresponding to frequencies in the range 30 PHz to 3 EHz). X-rays are primarily used for diagnostic medical imaging and crystallography. X-rays are a form of ionizing radiation and as such can be dangerous. In most languages it is called Röntgen radiation (or an equivalent name) after its discoverer Wilhelm Röntgen. X-ray - Physics. X-rays with a wavel ...

Including:

• X-ray - Physics
• X-ray - Detectors
• X-ray - Photographic plates
• X-ray - Geiger counters
• X-ray - Scintillators
• X-ray - Direct semiconductor detectors
• X-ray - Scintillator + Semiconductor detectors
• X-ray - Visibility to the Human Eye
• X-ray - Medical uses
• X-ray - History
• X-ray - Tesla
• X-ray - Hertz
• X-ray - Röntgen
• X-ray - Edison
• X-ray - The 20th century and beyond

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Sir Aaron Klug, OM, FRS (born 11 August 1926 in Zelvas, Lithuania ) is a Lithuanian-born British physicist and chemist, and winner of the 1982 Nobel Prize in Chemistry for his development of crystallographic electron microscopy. Having moved to South Africa at the age of two, he graduated with a degree in science at the University of Witwatersrand and studied crystallography at the University of Cape Town before moving to England, completing his ...

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Cloud seeding is the attempt to change the amount or type of precipitation that falls out of clouds or the structure of clouds by dispersing substances into the air which allow water droplets or ice crystals to form more easily. The most common chemicals used for cloud seeding include silver iodide and dry ice (frozen carbon dioxide). These chemicals may be dispersed by aircraft or by dispersion devices located on the ground. For example, silver iodide flares will be ignited as an aircraft flies through a cloud. When released b ...

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A crystal system is a category of space groups, which characterize symmetry of structures in three dimensions with translational symmetry in three directions, having a discrete symmetry group. A major application is in crystallography, to categorize crystals, but by itself the topic is one of 3D Euclidean geometry. There are 7 crystal systems: Triclinic, all cases not satisfying the requirements of any other system; thus there is no other symmetry than translational symmetry, or the only extra kind is inversion.Including:

• Crystal system - Crystallographic point group
• Crystal system - Overview of point groups by crystal system
• Crystal system - Classification of lattices

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Crystalline solids have a very regular atomic structure: that is, the local positions of atoms with respect to each other are repeated at the atomic scale. These arrangements are called crystal structures, and their study is called crystallography. However, most crystalline materials are not perfect: the regular pattern of atomic arrangement is interrupted by crystal defects. The various types of defects are enumerated here. Crystallographic defect - Point defects. Vacancies are sites which are usuall ...

Including:

• Crystallographic defect - Point defects
• Crystallographic defect - Line defects
• Crystallographic defect - Planar defects
• Crystallographic defect - Bulk defects
• Crystallographic defect - Books

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In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. A crystal structure is composed of a unit cell, a set of atoms arranged in a particular way; which is periodically repeated in three dimensions on a lattice. The spacing between unit cells in various directions are called its lattice parameters. The symmetry properties of the crystal are embodied in its space group. A crystal's structure and symmetry play a role in determining many of its properties, such as cleavage, el ...

Including:

• Crystal structure - Unit cell
• Crystal structure - Crystal system
• Crystal structure - Classification of lattices
• Crystal structure - Point and space groups
• Crystal structure - Defects in crystals
• Crystal structure - Crystal symmetry

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William Hallowes Miller (April 6, 1801 – May 20, 1880), British mineralogist and crystallographer, was born at Velindre near Llandovery, Carmarthenshire. He was educated at St John's College, Cambridge, where he graduated in 1826 as fifth wrangler, and became a fellow in 1829. For a few years he was occupied as a college tutor and during this time he published treatises on hydrostatics and hydrodynamics. He also gave special attention to crystallography, and on the resignation of William Whewell he succeeded in 1832 to ...

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Emanuel Swedenborg ▶ (help·info) (né Swedberg) (January 29, 1688 – March 29, 1772) was a Swedish scientist, philosopher and mystic. Swedenborg had a prolific career as an inventor and scientist. Then at age fifty-six he claimed that he entered into a new spiritual phase of his life, experiencing first dreams, and later visions of a spiritual world where he talked with angels and spirits, many of them from the Bible, such as Moses and Jesus. Amongst other t ...

Including:

• Emanuel Swedenborg - Claims of veracity
• Emanuel Swedenborg - Biography
• Emanuel Swedenborg - Early life
• Emanuel Swedenborg - Scientific period
• Emanuel Swedenborg - The crisis
• Emanuel Swedenborg - Visions and spiritual insights
• Emanuel Swedenborg - Scriptural commentary and writings
• Emanuel Swedenborg - Accomplishments
• Emanuel Swedenborg - Scientific contributions
• Emanuel Swedenborg - Psychic abilities
• Emanuel Swedenborg - Theology
• Emanuel Swedenborg - Philosophical and religious influence

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William Hyde Wollaston (August 6, 1766 – December 22, 1828) was an English chemist who is famous for discovering two chemical elements and for developing a way to process platinum ore. William Hyde Wollaston - Life. He was born in East Dereham, Norfolk and in 1793 obtained a doctorate in medicine from Cambridge University. During his studies there he became interested in chemistry, crystallography, metallurgy and physics. The mineral Wollastonite is named after him. In 1800 he left medicine and concentrat ...

Including:

• William Hyde Wollaston - Life
• William Hyde Wollaston - Work
• William Hyde Wollaston - Honours

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X-ray crystallography is a technique in crystallography in which the pattern produced by the diffraction of X-rays through the closely spaced lattice of atoms in a crystal is recorded and then analyzed to reveal the nature of that lattice. This generally leads to an understanding of the material and molecular structure of a substance. The spacings in the crystal lattice can be determined using Bragg's law. The electrons that surround the atoms, rather than the atomic nuclei themselves, are the entities which physically interact with t ...

Including:

• X-ray crystallography - Inorganic Structures
• X-ray crystallography - Organic Structures

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Allan McLeod Cormack (February 23, 1924 – May 7, 1998) was a South African-born American physicist who shared a part of the 1979 Nobel Prize in Physiology or Medicine for his work on the computerized axial tomography (CAT) scan. Cormack was born in Johannesburg, South Africa. He attended the Rondebosch Boys High School, where he was active in the debating and tennis teams. He received his B.Sc. in physics in 1944 from the University of Cape Town and his M.Sc. in crystallography in 1945 from the same institution. He worked at ...

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Inorganic chemistry is the branch of chemistry concerned with the properties and reactions of inorganic compounds. This includes all chemical compounds except the many which are based upon chains or rings of carbon atoms, which are termed organic compounds and are studied under the separate heading of organic chemistry. The distinction between the two disciplines is not absolute and there is much overlap, most impo ...

Including:

• Inorganic chemistry - Categories of inorganic chemical reactions
• Inorganic chemistry - Branches of inorganic chemistry

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Biophysics (also biological physics) is an interdisciplinary science that applies the theories and methods of physical sciences to questions of biology. Biophysics research today comprises a number of specific biological studies, which do not share a unique identifying factor, or subject themselves to clear and concise definitions. This is the result of biophysics' relatively recent appearance as a scientific discipline. The studies included under the umbrella of biophysics range from sequence comparison to neural networ ...

Including:

• Biophysics - Overview
• Biophysics - Topics in biophysics and related fields
• Biophysics - Famous biophysicists
• Biophysics - Other notable biophysicists

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Quartz is the most abundant mineral in the Earth's continental crust. It has a hexagonal crystal structure made of trigonal crystallized silica (silicon dioxide, SiO2), with a hardness of 7 on the Mohs scale. Density is 2.65 g/cm³. The typical shape is a six-sided prism that ends in six-sided pyramids, although these are often twinned, distorted, or so massive that only part of the shape is apparent from a mined specimen. Additionally a bed is a common form, particularly for varieties such as amethyst, where the cry ...

Including:

• Quartz - Varieties
• Quartz - History
• Quartz - Piezoelectricity

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Sulfur (or sulphur; see spelling below) is the chemical element in the periodic table that has the symbol S and atomic number 16. It is an abundant, tasteless, odorless, multivalent non-metal. Sulfur, in its native form, is a yellow crystaline solid. In nature, it can be found as the pure element or as sulfide and sulfate minerals. It is an essential element for life and is found in two amino acids. Its commercial uses are primarily in fertilizers but it is also widely used in gunpowder, matches, insecticides and fungici ...

Including:

• Sulfur - Notable characteristics
• Sulfur - Applications
• Sulfur - Biological role
• Sulfur - Environmental Impact
• Sulfur - History
• Sulfur - Occurrence
• Sulfur - Compounds
• Sulfur - Isotopes
• Sulfur - Precautions
• Sulfur - Spelling

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X-ray - Photographic plates. The detection of X-rays is based on various methods. The most commonly known method are a photographic plate, or cassette, and rare earth screens. The X-ray photographic plate is frequently used in hospitals to produce images of the internal organs and bones of a patient. The part of the patient to be X-rayed is placed between the X-ray source and the photographic plate to produce what is a shadow of all the internal structure of that particular part of the body being X-rayed. ...

See also:

X-ray, X-ray - Physics, X-ray - Detectors, X-ray - Photographic plates, X-ray - Geiger counters, X-ray - Scintillators, X-ray - Direct semiconductor detectors, X-ray - Scintillator + Semiconductor detectors, X-ray - Visibility to the Human Eye, X-ray - Medical uses, X-ray - History, X-ray - Tesla, X-ray - Hertz, X-ray - Röntgen, X-ray - Edison, X-ray - The 20th century and beyond

Read more here: » X-ray: Encyclopedia II - X-ray - Detectors

Representation theory divides into subtheories depending on the kind of group being represented. The various theories are quite different in detail, though some basic definitions and concepts are similar. The most important divisions are: Finite groups — Group representations are a very important tool in the study of finite groups. They also arise in the applications of finite group theory to crystallography and to geometry. If the field of scalars of the vector space has characteristic p, and if p divides ...

See also:

Group representation, Group representation - Branches of representation theory, Group representation - Basic definitions, Group representation - Simple example, Group representation - Equivalence of representations, Group representation - Reducibility, Group representation - Character theory, Group representation - Generalizations, Group representation - Set-theoretical representations, Group representation - Representations in other categories

Read more here: » Group representation: Encyclopedia II - Group representation - Branches of representation theory