Brightness and colour

We have two kinds of colour producing light sources, the emitter (flames or sparks) and the reflector (smoke or parachute, flags, etc.). Here the former is described since it is the most important. 

The emitter is characterized by three concepts brilliancy, hue and purity. Hue means the kind of colour, i.e. red, yellow, green, blue, violet etc. Purity means the degree of whiteness of a colour. 

The brilliancy of an emitter, which is visible as if it were a flat emitting surface, is denoted by the candle powder per unit area of the surface  

Illuminous intensity of light (cd)/ Area of emitter which is rectanglar to the direction of the observer(m ) 

More precisely the brilliancy differs according to the part of the emitter and the direction of the observer. 

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Finally the aminothiadiazoles have been used to prepare bright red dyes. In particular the dyes derived from 5-substituted 2-amino-l,3,4-thiadiazoles (52) (70GEP2028396) and the 3-substituted 5-amino-l,2,4-thiadiazoles (53) (70GEP2006131) by coupling with dialkyl-anilines are neutral to bluish-reds of outstanding brightness and colour strength. 

Man has two kinds of optic nerve cells in his eyes pyramids and bars. The former respond to the brightness and colour of a light, but the latter have no colour sense, and only sense black and white like a monochrome photograph. Almost in the middle of the retina there is a narrow place where only the pyramids concentrate and no bars are found here the sense is sharpest. The greater the distance from this place, the more the density of the pyramids decreases and that of the bars increases. 

These bright and colourful frogs are endemic to Central America and to the Northwestern part of South America. The skin secretions are used by the indigenous people as arrow poison for hunting especially in the Choco region of Columbia (ref. 12). 

Shen F, He F, Lu D et al (2006) Bright and colour stable white polymer light-emitting diodes. Semi Sci Tech 22 L16-L19... 

C a series of even-spaced bright and coloured lines D a series of bright and coloured lines that converge at high frequency... 

Drzaic, P. S., Wiley, R. C., and McCoy, J., High brightness and colour contrast displays constructed from nematic droplet/polymer films incorporating dichroic dyes, Proc. SPIE, 1080, 41, 1989. 

Phthalein reaction. Fuse together carefully in a dry test-tube a few crystals of phthalic acid or of a phthalate and an equal quantity of ph tol moistened with 2 drops of cone. H2SO4. Cool, dissolve in water and add NaOH solution in excess the bright red colour of phenolphthalein in alkaline solution is produced. 

The contents of B, which act as a control, are treated with mercuric chloride in order to inhibit the action of the enzyme, and then 10 ml. of urease solution are added. The solution is diluted with water and ammonium chloride added (in order to balance the ammonium chloride subsequently formed in A). Meth) l-red is then added and the solution is titrated with Mj 10 HCl from a second burette B until a bright red colour is obtained. 

Thymus ALuticJnmi, the so-called Spanish wuod marjoram, yields an oil of thyme which has been examined recently hy Dorrousoro,- It ban a bright vnllow colour, turning darker with age, and a camphoracc-... 

Impart a bright and intense colour to a substrate by a process which at least temporarily destroys any crystal structure of the colouring substances. Dyes are transparent and easy to disperse and process. Dyes are incompatible with polyolefins, having a tendency to bleed and plate out. Due to the solubility and... 

The discovery in 1979 of the benzodifuranone chromogen (1.14) and its exploitation in red disperse dyes for polyester fibres [23,24] emerged from ICI research towards new chromogens of high colour value, brightness and substantivity to overcome the relative weakness of anthraquinones and dullness of monoazo alternatives in the red disperse dye area. A striking improvement in build-up properties was found by introducing asymmetry... 

Derivatives of triphenylmethane were among the earliest synthetic colorants, and are still in demand where bright, intense colours are needed without the necessity for outstanding fastness to light and chemical reagents. Basic dyes of this type, as well as other cationic dyes, are suitable for dyeing conventional acrylic fibres, on which they show better fastness properties than on natural fibres. The photodegradation of triphenylmethane dyes has been reviewed [42]. 

Ammonium ceric sulphate serves as a powerful oxidizing agent in an acidic medium. The salt has a bright yellow colour and so its solution. On reduction, the resulting cerous salt obtained is colourless in appearance and, therefore, strong solutions may be considered as self-indicating. In general practice, 0.05 N solutions are employed invariably for estimations. As this concentration is very dilute for observation of the respective end-point, hence the inclusion of an appropriate indicator becomes necessary. The oxidation reaction involved may be expressed as follows ... 

One of the simplest natural flavonoids is the flavanone liquiritigenin, a material that contributes to the bright yellow colour of liquorice root. Liquiritigenin may be synthesized readily, as shown, by a two-stage process starting from the phenolic ketone and aldehyde. 

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