Couplers

Inspection of wheels, automatic coupler equipment, assemblies of cars trucks, axles of wheel pairs, cardan shafts, tank cars, turbines parts and power facilities of locomotives. 

Fig. 1 shows the block diagram of the vibrometer, in which the most sensible to small phase variations interferometric scheme is employed. It consists of the microwave and the display units. The display unit consists of the power supply 1, controller 2 of the phase modulator 3, microprocessor unit 9 and low-frequency amplifier 10. The microwave unit contains the electromechanical phase modulator 3, a solid-state microwave oscillator 4, an attenuator 5, a bidirectional coupler 6, a horn antenna 7 and a microwave detector 11. The horn antenna is used for transmitting the microwave and receiving the reflected signal, which is mixed with the reference signal in the bidirectional coupler. In the reference channel the electromechanical phase modulator is used to provide automatic calibration of the instrument. To adjust the antenna beam to the object under test, the microwave unit is placed on the platform which can be shifted in vertical and horizontal planes. 

The pulser/receiver is completely shielded and therefore receives no noise coming from the PC components. The input connector is a Lemo 00 coupler. The extremely low noise amplifier with a maximum amplification of about 90 dB accommodates very small signals. A precise gain setting is possible up to 106 dB. 

Figure B2.1.1 Femtosecond light source based on an amplified titanium-sapphire laser and an optical parametric amplifier. Symbols used P, Brewster dispersing prism X, titanium-sapphire crystal OC, output coupler B, acousto-optic pulse selector (Bragg cell) FR, Faraday rotator and polarizer assembly DG, diffraction grating BBO, p-barium borate nonlinear crystal.

Figure C2.15.17. The Mach-Zender modulator. A 3 dB coupler splits tlie input wave into tlie two anns of tlie device. The output 3 dB combiner recombines half tlie wave witli its phase-shifted counteriDart. By adjusting Fq tlie output transmission can be rapidly modulated.

Coupled chromophores Coupler Couplers Coupling Coupling agents... 

Q. Coupler, Memo J8383, Ronningen-Peter, Portage, Mich., Aug. 27, 1981. 

Oxidation H ir Colorant. Color-forming reactions are accompHshed by primary intermediates, secondary intermediates, and oxidants. Primary intermediates include the so-called para dyes, -phenylenediamine, -toluenediamine, -aminodiphenylamine, and p- am in oph en o1, which form a quinone monoimine or diimine upon oxidation. The secondary intermediates, also known as couplers or modifiers, couple with the quinone imines to produce dyes. Secondary intermediates include y -diamines, y -aminophenols, polyhydroxyphenols, and naphthols. Some of the more important oxidation dye colors are given in Figure 1. An extensive listing is available (24,28). 

The mechanism of oxidative dyeing involves a complex system of consecutive, competing, and autocatalytic reactions in which the final color depends on the efficiency with which the various couplers compete with one another for the available diimine. In addition, hydrolysis, oxidation, or polymerization of diimine may take place. Therefore, the color of a mixture caimot readily be predicted and involves trial and error. Though oxidation dyes produce fast colors, some off-shade fading does occur, particularly the development of a red tinge by the slow transformation of the blue indamine dye to a red phenazine dye. 

DimethyIhyda.ntoins. Some 5,5-dimethylhydantoin derivatives such as (22) have been patented as color photographic couplers (104) ... 

It is common to employ microwave power monitoring by means of a dual-directional coupler in the waveguide transmission system between the power tube and the useful load. Part of the coupled signals may be used for examination with spectmm analy2ers, frequency meters, and other microwave instmmentation for special purposes. Generally, this is not necessary in a practical appHcation. Many microwave measurement techniques have been described (59,60). AvailabiHty of components, plumbing, and instmmentation is weU described in trade journals. 

Naphthalenediol. This diol is made by the hydrolytic desulfonation of 2,3-naphthalenediol-6-sulfonic acid at ca 180°C. It is used as a coupler forming a2o dyes which are appHed in reprographic processes. 

A number of A/-acyl-. A/-alkyl-, and /V-arylamin on apbtbalenol sulfonic acids are used as couplers for a2o dyes. Examples of such intermediates are shown in Table 8. 

Hydroxy-2-Naphthalenecarboxylic Acid. l-Hydroxy-2-naphthoic acid is made similarly to the isomer (2-hydroxy-1-naphthoic acid) by reaction of dry sodium 1-naphthalenolate with CO2 in an autoclave at ca 125°C. It has been used in making triphenylmethane dyes and metalli able a2o dyes. Alkylamides and arylamides of l-hydroxy-2-naphthalenecarboxyhc acid are cyan couplers, ie, components used in indoaniline dye formation in color films (see Color PHOTOGRAPHY). 

Fig. 1. Representative device configurations exploiting electrooptic second-order nonlinear optical materials are shown. Schematic representations are given for (a) a Mach-Zehnder interferometer, (b) a birefringent modulator, and (c) a directional coupler. In (b) the optical input to the birefringent modulator is polarized at 45 degrees and excites both transverse electric (TE) and transverse magnetic (TM) modes. The appHed voltage modulates the output polarization. Intensity modulation is achieved using polarizing components at the output.

In most color photographic products, organic compounds such as couplers or redox dye releasers are added to the melted emulsions before coating. These compounds are essential to the development reactions that produce the dye molecules composing color images. 

Phloroglucinol is Hsted in the Colourindex as Cl Developer 19. It is particularly valuable in the dyeing of acetate fiber but also has been used as a coupler for azoic colors in viscose, Odon, cotton (qv), rayon, or nylon fibers, or in union fabrics containing these fibers (157). For example, cellulose acetate fabric is treated with an aromatic amine such as (9-dianisidine or a disperse dye such as A-hydroxyphenylazo-2-naphthylamine and the amine diazotizes on the fiber the fabric is then rinsed, freed of excess nitrite, and the azo color is developed in a phloroglucinol bath at pH 5—7. Depending on the diazo precursor used, intense blue to jet-black shades can be obtained with excellent light-, bleach-, and mbfastness. 

Amin ophen o1 has been used as a stabilizer of chlorine-containing thermoplastics (153), although its principal use is as an intermediate in the production of 4-aniino-2-hydroxybenzoic acid [65-49-6] a tuberculostat. This isomer is also employed as a hair colorant and as a coupler molecule in hair dyes (154,155). 

The Fuji CopiArt monochrome proofing system is based on the photogeneration of color from leuco dyes or diazo-coupling (35). CopiArt includes both positive and negative working systems (Fig. 6). For the positive working system, a diazo compound (6) reacts with a coupler (7) as shown. 

Fig. 6. CopiArt proofing system (a) stmcture of positive working system, where A = organic base, = coupler, Q = microcapsule, and = diazo compound and (b) stmcture of negative working system, where A = photoinitiator, = leuco dye, Q — microcapsule, and...

A lower alkyl or alkoxy group substituted in the ortho or meta position to an amino group may promote coupling. Good couplers are obtained from dimethylaruline when lower alkyl, lower alkoxy, or both groups are present in the 2- and 5-position. 

Technologically, the most important examples of such couplers are 1-naphthylamine, 1-naphthol, and sulfonic acid derivatives of 1-naphthol (Fig. 2). Of great importance in the dyestuff industry are derivatives of l-naphthol-3-sulfonic acid, such as H-acid (8-amino-l-naphthol-3,6-disulfonic acid [90-20-0])... 

The azo coupling reaction proceeds by the electrophilic aromatic substitution mechanism. In the case of 4-chlorobenzenediazonium compound with l-naphthol-4-sulfonic acid [84-87-7] the reaction is not base-catalyzed, but that with l-naphthol-3-sulfonic acid and 2-naphthol-8-sulfonic acid [92-40-0] is moderately and strongly base-catalyzed, respectively. The different rates of reaction agree with kinetic studies of hydrogen isotope effects in coupling components. The magnitude of the isotope effect increases with increased steric hindrance at the coupler reaction site. The addition of bases, even if pH is not changed, can affect the reaction rate. In polar aprotic media, reaction rate is different with alkyl-ammonium ions. Cationic, anionic, and nonionic surfactants can also influence the reaction rate (27). 

In mordant dyes, phenols, naphthols, and enolizable carbonyl compounds, such as pyrazolones, are generally the couplers. As a rule, 2 1 metal complexes are formed ia the afterchroming process. A typical example of a mordant dye is Eriochrome Black T (18b) which is made from the important dyestuff iatermediate nitro-l,2,4-acid, 4-amiQO-3-hydroxy-7-nitro-l-naphthalenesulfonic acid [6259-63-8]. Eriochrome Red B [3618-63-1] (49) (Cl Mordant Red 7 Cl 18760) (1, 2,4-acid — l-phenyl-3-methyl-5-pyrazolone) is another example. The equiUbrium of the two tautomeric forms depends on the nature of the solvent. 

Dyes with OjO -hydroxycarboxyazo and OjO -hydroxyaminoazo ligands are important for yeUow shades. Anthranilic acid [118-92-3] is used advantageously with various couplers. OjO -Hydroxyaminoazo dyes are also used to obtain green and brown shades. An example is Monochrome Brown EB [3564-15-6] (54) (Cl Mordant Brown 1 Cl 20110) an unsymmetrical primary disazo dye. 

Commercial Disperse Azo Dyes. The first proposal to use insoluble dyes in suspension in an aqueous foam bath, ie, disperse dyes, to dye cellulose acetate was in 1921 (60). Commercialization of disperse dyes began in 1924 with the introduction of the Duranol dyes by British Dyestuffs Corporation (61) and the SRA dyes by British Celanese Company (62). In contrast to the acid monoazo dyes, derivatives of benzene rather than of naphthalene are of the greatest importance as coupling components. Among these components mono- and dialkylariifines (especially A/-P-hydroxyethyl-and A/-(3-acetoxyethylanifine derivatives) are widely used couplers. Nitrodiazobenzenes are widely used as diazo components. A typical example is CeUiton Scarlet B [2872-52-8] (91) (Cl Disperse Red 1 Cl 11110). 

Couplers which form scarlet dyes with 4-nitroani1ine and red dyes with 2-amiQO-6-nitrobenzothiazole yield blue dyes with 3-amiQo-5-nitro-2,l-benzisothiazole [14346-19-1]. 

A number of other heterocycHc diazo components such as thiazole, iadazole, thiophenes, and thiadiazole types (see Fig. 1), as well as heterocycHc couplers, ie, 6-hydroxy-2-pyridinone [626-06-2] barbituric acid [67-52-7] and tetrahydroquiaoline [25448-04-8] h.2L e been cited ia the Hterature (90,91). Reviews on disperse dyes have been pubUshed (92,93). 

Basic Red 18 (131), Basacryl Red X-NL [14097-03-17 is an example of a pendant cationic azo dye, ia which a localized positive charge is not conjugated with the chromophoric system. /V-Kthy1-/V-(2-ch1oroethy1)ani1ine [92-49-9] reacts with trimethyl amine to form the ammonium salt coupler. The diazo component ia Basic Red 18 is 2-ch1oro-4-nitroani1ine [121 -87-9]. 

Subtractive dye precursors (couplers) that could be immobilized in each of the silver containing layers were sought, so that dye formation in all layers could proceed simultaneously rather than successively. The first of these to be commercialized were in Agfacolor Neue and Ansco Color films, introduced soon after Kodachrome film. These reversal working films contained colorless couplers that were immobilized (ballasted) by the attachment of long paraffinic chains. The addition of sulfonic or carboxyUc acid groups provided the necessary hydrophilicity to make them dispersible as micelles in aqueous gelatin. 

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