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Index (C)

CA - CC

CD - CF

CG - CJ

CK - CN

COA - CON

COO - CR

CS - CV

CW - CZ

Moment of truth
The word 'nanotechnology' is first coined by University of Tokyo researcher Norio Taniguchi back in 1974.


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corona Astron.
The outermost atmosphere of a star, consists of very hot gas heated to temperatures millions of degrees.
Sun's corona The Sun's corona is clearly visible when the Moon completely covers the sun during total solar eclipse (left).The temperature of the surface of the sun is about 6000C, whereas corona temperature can reach up to a million centigrade. There is still no satisfactory explanation why the corona is so much hotter than the sun's surface.

cosmic inflation Astron.
A theory of cosmology that explains the very early stage of the Big Bang process that formed the universe. It is introduced in the early 1980s by theoretical physicists Alan Guth and Alexei Starobinski. The theory states that at the very early stage of Big Bang, the universe underwent a very rapid expansion, with an increase in size of a factor of 1025 in about 10-32 second. During this period, the universe expanded from the size of a proton to the size of a grapefruit. Following after this stage, the universe would resume its normal, decelerating expansion.

The theory was introduced in order to explain the smoothness of the universe expansion in all direction as it is observed today, with similar distribution of galaxies in all direction. The rapid expansion, that doubled the size of the universe every 10-34 second as light travelled over a distance much less than the size of an atomic nucleus during the whole inflation period, removes all initial complexities and generates a smooth universe. The expansion energy is thought to have converted to form particles such as protons and electrons that subsequently form atoms and matter. The remnant energy was dispersed as the cosmic microwave background pervading the universe today.

cosmic ray Astron.
High-speed particles with an energy range of 109 GeV to more than 1020 GeV and originate from space. Most of these particles consist of protons (~80%) and alpha particle (~12%) while the remainder can be electrons, nuclei of oxygen, carbon, nitrogen and other heavier elements. Most of these particles are thought to originate with the Milky Way but those of extremely high energy (above 1018 GeV) are believed to have created at even more distant sources. The rays was first discovered by Viktor Hess in 1912 and these particles often interact with air molecules in the atmosphere to produced scattered paths and short-lived particles.

cosmic year Astron.
The time it takes the Sun to complete an orbit around the center of the Milky Way (galatic rotation). This is approximately equal to 225 million years.

coulombic interaction Chem., Phys.
Energy interaction between two point charges, acting along the line connecting the two charges and defines as:

Coulombic interaction

where r is the distance between two ions, q1 and q2 are the corresponding electric charges (in Coulombs) and e0 is the dielectric constant of a medium (electrical permitivity of space). Two opposite charged species will give an attractive interaction (negative U), while similar charged species give repulsive interaction (positive U).

counterion Chem.
An ion that is of opposite charge to another ionic species. A counterion is often necessarily present in a system in order to maintain the overall charge neutrality of the system. For example, sodium cation is a counterion for the chloride anion (and vice versa) in the sodium chloride solution.

covalent radius Chem.
Measure of the size of atom which forms part of a covalent bond. Usually the sum of two covalent radii should be the covalent bond length between two similar atoms. For instance, the covalent radius of hydrogen atom in the hydrogen gas (H2) is 37.07 pm (picometer) which is half of the H-H bond length. However, the covalent radius of an atom is not the same depending on its chemical environment and its covalent bonding with the other atom. Covalent radii can usually be measured by X-ray diffraction.

CPT symmetry Phys.
Abbreviation for Charge, Parity and Time Reversal symmetry, the hypothesis of the Standard Model of particle physics which states that the laws of physics do not change if all the interacting particles are replaced by their antiparticles of opposite charge (C), all the directions are reversed (P) and the time is reversed (T).

cryogenic pump Eng., Chem.
A vacuum pump in which pressure is reduced by condensing gases and vapors on cold surfaces. The low temperature of the surface can be maintained by liquid helium or other coolants such as liquid hydrogen, liquid nitrogen or dry ice. Depending on the coolant being used, pressure down to 10-8 mmHg (10-6 Pa) can be achieved.

The gases remained condensed as long as the surface is sufficiently cold. When the surface is saturated with the condensed gas, it will not be able to further condense any fresh leaks and pressure will subsequently increase. However, the surface can be regenerated by evaporating the gases by means of a machanical pump in the vacuum condition.

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