Arachidate

If an ideal solution is formed, then the actual molecular A is just Aav (and Aex = 0). The same result obtains if the components are completely immiscible as illustrated in Fig. IV-21 for a mixture of arachidic acid and a merocyanine dye [116]. These systems are usually distinguished through the mosaic structure seen in microscopic evaluation. 

Fig. IV-21. Surface pressure versus area for monolayers of immiscible components a monolayer of pure cadmium arachidate (curve 1) and monolayers of mixed merocyanine dye, MC2, and cadmium arachidate of molar ratio r = 1 10 (curve 2) 1 5 (curve 3), 1 2 (curve 4), and pure MC2 (curve 5). The subphase is 2.5 x 0 M CdC, pH = 5.5 at 20°C. Curve 3a (O) was calculated from curves 1 and 5 using Eq. IV-44. (From Ref. [116].)...

Fig. Vni-3. (a) Atomic force microscope (AFM) and (b) transmission electron microscope (TEM) images of lead selenide particles grown under arachidic acid monolayers. (Pi Ref. 57.)...

A unique but widely studied polymeric LB system are the polyglutamates or hairy rod polymers. These polymers have a hydrophilic rod of helical polyglutamate with hydrophobic alkyl side chains. Their rigidity and amphiphilic-ity imparts order (lyotropic and thermotropic) in LB films and they take on a F-type stmcture such as that illustrated in Fig. XV-16 [182]. These LB films are useful for waveguides, photoresists, and chemical sensors. LB films of these polymers are very thermally stable, as was indicated by the lack of interdiffusion up to 414 K shown by neutron reflectivity of alternating hydrogenated and deuterated layers [183]. AFM measurements have shown that these films take on different stmctures if directly deposited onto silicon or onto LB films of cadmium arachidate [184]. 

Another approach is to use the LB film as a template to limit the size of growing colloids such as the Q-state semiconductors that have applications in nonlinear optical devices. Furlong and co-workers have successfully synthesized CdSe [186] and CdS [187] nanoparticles (<5 nm in radius) in Cd arachidate LB films. Finally, as a low-temperature ceramic process, LB films can be converted to oxide layers by UV and ozone treatment examples are polydimethylsiloxane films to make SiO [188] and Cd arachidate to make CdOjt [189]. 

Figure Bl.19.28. Molecular-scale image (2 mu x 20 mu) of a barium arachidate bilayer. Image was produced by averaging six images, but without filtering data. (Taken from [135], figure 1.)...

Thermal stahility. Yor applications of LB films, temperature stability is an important parameter. Different teclmiques have been employed to study tliis property for mono- and multilayers of arachidate LB films. In general, an increase in temperature is connected witli a confonnational disorder in tire films and above 390 K tire order present in tire films seems to vanish completely [45, 46 and 45] However, a comprehensive picture for order-disorder transitions in mono- and multilayer systems cannot be given. Nevertlieless, some general properties are found in all systems [47]. Gauche confonnations mostly reside at tire ends of tire chains at room temperature, but are also present inside tire... 

Laurie acid Myristic acid Palmitic acid Stearic acid Arachidic acid... 

Arachidonic acid gets its name from arachidic acid the saturated C20 fatty acid isolated from peanut (Arachts hypogaea) oil... 

Type of oil Palmitic Stearic Olei Linoleic Linolenic Arachidic glc Wijs... 

LB Films of Long-Chain Fatty Acids. LB films of saturated long-chain fatty acids have been studied since the inception of the LB technique. The most stable films of long-chain fatty acids are formed by cadmium arachidate deposited from a buffered CdCl2 subphase. These films, considered to be standards, have been widely used as spacer layers (23) and for examining new analytical techniques. Whereas the chains are tilted - 25° from the surface normal in the arachidic acid, CH2(CH2) gCOOH, films (24), it is nearly perpendicular to the surface in the cadmium arachidate films (25). 

Also contains 0.5% each of arachidic andbehenic acid (C22). 

The new approach for development of pH sensor with wide acidity range (2.5 M H SO - pH 5.5) based on the use of Congo Red and Benzopurpurin 4B immobilized in polyamido- or arachidic acid nanosized sensitive matrix will be demonstrated. 

The use of arachidic acid and different amphiphilic calixarenes for modifying of field effect transistor sensors and determination of some volatile organic contaminants will be considered. 

Even before heating all the acids rapidly appeared as blue zones on a yellow-blue background. After heating tartaric acid QiRf 2—5) and maUc acid hRf 5 — 10) retained their color while lactic acid hRf 30 — 35), succinic acid hRf 35—40), pimelic acid hRf 50), maleic acid hRf 55), suberic acid hRf 55 — 60), benzoic acid hRf 80 — 85), stearic acid hRf 85 — 90) and arachidic acid hRf 85—90) appeared as pale yellow zones on a blue-yellow background (Fig. 1). The detection limits lay at 1 to 2 pg substance per chromatogram zone. 

Fig. 1 Schematic representation of the chromatographic separation of carboxylic acids. Maleic acid (1), pimelic acid (2), succinic acid (3), benzoic acid (4), malic acid (5), tartaric acid (6), lactic acid (7), stearic acid (8), arachidic acid (9), suberic acid (10), mixture (M).

Detection and result The chromatogram was freed from mobile phase and immersed in the reagent solution for 1 s. Arachidic acid (hRf 15-20), stearic acid hR( 30 — 35), palmitic acid hRf 50—55), myristic acid (hRf 60 — 65) and lauric acid (hRf 70 — 75) appeared as pink zones on a reddish background. 

Detection and result The chromatogram was freed from mobile phase and immersed for 1 s in the reagent solution. Arachidic acid (hRf 35 — 40), stearic acid... 

Erdnuss, /. earthnut, ground nut (most commonly the peanut, Arachia hypogaea). -fil, n. peanut oil, arachis oil. -saure, /. arachidic acid (old name),... 

Arabinose, configuration of. 982 Kiliani-Fischer synthesis on. 995 Arachidic acid, structure of, 1062 Arachidonic acid, eicosanoids from, 1069-1070... 

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