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cutoff wavelength mowj-tul-e boré Fr.: longueur d'onde de coupure Wavelength at which the transmittance of a filter, or the detectivity of a detector, has fallen to one-half its peak value. → cutoff; → wavelength. |
cyanide siyânur (#) Fr.: cyanure A chemical compound that contains the → cyano radical, -CN. Most cyanides are highly toxic. |
cyano radical râdikâl-e siyâno Fr.: radical cyano A diatomic chemical radical composed of carbon and nitrogen atoms. The triple bonds of C to H leave one electron available, which makes the CN radical very reactive. Organic molecules with the -CN group are potential sources of → prebiotic amino acids. Same as the → CN molecule. The CN radical was first identified by Gay-Lussac, who in 1815 published an extensive study of the derivatives of prussic acid (→ hydrogen cyanide). He showed that the cyano radical remained intact throughout a series of chemical transformations. Also called cyanogen radical. |
cyano- siyâno- (#) Fr.: cyano- 1) A combining form meaning "blue, dark blue," used in the formation of
compound words. Also cyan- before a vowel. From Gk. kyanos "dark blue, lapis lazuli," because of its presence in the Prussian blue, Fe7(CN)18, a dye which was first accidentally made around 1706, by heating substances containing iron and carbon and nitrogen. |
cyanogen siyânožen (#) Fr.: cyanogène 1) A colorless, very poisonous, flammable gas with a smell of bitter almonds.
Chemical formula: C2N2. It was discovered by
Louis Joseph Gay-Lussac (1778-1850) in 1848. |
cyanogen band bând-e siyânožen (#) Fr.: bande de cyanogène An → absorption band of molecular origin characterizing the spectra of → late-type stars (G0 and later, e.g. → S star). → Cyanogen absorption is an important → luminosity criterion for → low-mass stars, and is more pronounced in → giant stars than in → dwarf stars of the same → spectral type. |
cycle carx (#), carxé (#) Fr.: cycle 1) A sequence of changes that are repeated regularly, such as revolution, rotation,
vibration, oscillation, wave motion. From L.L. cyclus, from Gk. kyklos "circle, wheel," from PIE base *kw(e)-kwl-o- "wheel, circle," from *kwel- "to turn, move around, sojourn, dwell," (cf. Av. caxra- "wheel," caraiti "he moves, approaches;" Mod.Pers. carx "wheel;" Skt. cakra- "wheel, circle; cycle," carati "he moves, wanders;" Gk. polos "axis of a sphere," polein "move around;" L. colere "to dwell in, to cultivate, move around," colonus "farmer, settler;" O.E. hweol "wheel;" Rus. koleso "awheel"). Carx "every thing performing a circulatory motion; a wheel; a cart," Mid.Pers. chr "wheel," Parthian cxr "wheel," Ossetic, Khotanese calx "wheel," Av. caxra- "wheel," cognate with Gk. kyklos "circle, wheel," as above. Carxé from carx + nuance suffix -é. |
cyclic carxe-yi (#) Fr.: cyclique Of, pertaining to, or constituting a cycle or cycles. |
cyclic coordinate hamârâ-ye nâdidé engâshté Fr.: coordonnée ignorée Same as → ignorable coordinate. → cyclic; → coordinate. |
cyclic group goruh-e carxe-yi Fr.: groupe cyclic A group in which each element can be expressed as a power of any other element. |
cyclic process farâravand-e carxe-yi Fr.: processus cyclique Any sequence of changes in a → thermodynamic system that returns the system into its → initial → state. |
cyclic quadrilateral cahârbar-e carxe-yi Fr.: quadrilatère cyclique A quadrilateral in which all four vertices lie on the circumference of a circle. → cyclic; → quadrilateral. |
cycloid carxzâd (#) Fr.: cycloïde The curve traced by a point on the circumference of a circle that rolls along a straight line. The cycloid has a → cusp at every point where it touches the straight line. The distance between cusps is 2πR, where R is the radius of the circle. Cycloid, from Gk. kykloeides "circular," fr. kyklos "circle," → cycle + eides "form," → -oid. Carxzâd, from carx "wheel, circle," → cycle + zâd "produced, created, born," from zâdan "give birth" (Av. zan- "to bear, give birth to a child, be born," infinitive zazâite, zâta- "born," cf. Skt. janati "begets, bears," Gk. gignesthai "to become, happen" L. gignere "to beget," gnasci "to be born," PIE base *gen- "to give birth, beget"). |
cyclone carxand (#) Fr.: cyclone Any circulatory wind system in the atmosphere in which the motion is anticlockwise in the northern hemisphere (that is in the same sense as that of Earth) and clockwise in the southern hemisphere, around a center of low pressure. From Gk. kyklon "moving in a circle, whirling around," pr.p. of kykloun "move in a circle, whirl," from kyklos "circle," cognate with Pers. carx→ cycle. Carxand "moving in a circle," from carxidan→ rotate, from carx, → cycle. |
cyclonic carxandi Fr.: cyclonique Having a sense of rotation about the local vertical the same as that of the Earth's rotation. More specifically, as viewed from above, → counterclockwise in the Northern Hemisphere, → clockwise in the Southern Hemisphere, and undefined at the equator. The opposite of → anticyclonic (Meteorology Glossary, American Meteorological Society). |
cyclotron siklotron (#) Fr.: cyclotron An → accelerator in which charged subatomic particles generated at a central source are accelerated to acquire energies up to several tens of millions of → electron-volts. The cyclotron consists of two flat, semicircular metal boxes or electrodes, called dees or D's because of their shape. An alternating electric field between the dees continuously accelerates the particles from one dee to the other, while the magnetic field bends their direction guiding them in a circular path. As the speed of the particles increases, so does the radius of their path, and the particles spiral outward. See also → cyclotron frequency, → synchrotron. |
cyclotron frequency basâmad-e siklotron Fr.: fréquence cyclotron The frequency with which a → non-relativistic particle of charge q and mass m turns in a cyclotron with → uniform magnetic field B. The equality of the → centripetal force to the → Lorentz force leads to the expression: by: fcycl = qB/2πm. For → relativistic case, the frequency is smaller and is called → synchrotron frequency. |
cyclotron radius šo'â'-e siklotron Fr.: rayon de cyclotron Same as → Larmor radius. |
Cygnus Mâkiyân (#) Fr.: Cygne The Swan. A prominent northern → constellation that lies in the glowing band of the Milky way, east of Lyra and north of Vulpecula, and represents a swan. The brightest stars of Cygnus form a cross, so it is also known as the Northern Cross. Abbreviation: Cyg, genitive: Cygni. From L. cygnus "swan," from Gk. kuknos. Mâkiyân "a hen, fowl." |
Cygnus A Mâkiyân A Fr.: Cygnus A The strongest extragalactic radio source in the sky approximately 109 light-years away in the → constellation → Cygnus. Also called 3C 405. → Cygnus. |
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