Chemical-retting

Chemical retting iuvolves immersion of the dried plants iu a tank with a solutiou of chemicals, such as sodium hydroxide, sodium carbouate, soaps, or mineral acids. The fibers are looseued iu a few hours, but close coutrol is required to preveut deterioratiou. Chemical retting is more expeusive and does not produce a superior fiber to that obtained from biological retting. 

Chemical retting consists of softening the tissues by boiling with dilute oxalic acid or alkali either at atmospheric or higher pressure. After treatment, the soluble bodies formed by the degradation of the less-resistant tissues are washed away. The process is considerably quicker than those relying upon natural fermentation. After retting, by whichever means, the residual tissues are passed between squeeze rollers to remove the excess liquor, and are then well washed in fresh water and dried. 

Chemical retting has also been studied using 1, 4, and 7% sodium hydroxide to separate... 

Soutar and Brydon s results show no significant difference between H. cannabinus and H. sabdariffa, which is, perhaps, surprising in view of the difference between the two jute varieties, but the acetyl content does appear to offer a means of differentiating between jute and kenaf. For such a comparison to be valid, of course, there must have been no prior treatment of the fiber with alkali, which occasionally happens in chemical retting experiments. 

Nettle stalk Chemical retting, water retting mechanical separation Vat enzyme treatment, spray enzyme treatment EDTA Viscozyme L, Pectinex Ultra SP-L, ROO40B Ll/6 Chemical, tensile, morphological properties 38... 

The plant is harvested by hand sickle and, after defoUation, is stripped and scraped by hand or machine decorticated. Because of the high gum (xylan and araban) content of up to 35%, retting is not possible. The fibers are separated chemically by boiling in an alkaline solution in open vats or under pressure, then washed, bleached with hypochlorite, neutralized, oiled to facUitate spinning, and dried. 

Mesta Retting and beating/chemical Same as jute —... 

It follows from the equation above that c, if Fv.rec Fvj This means that for a recycle stream much larger than the feed stream, the catalyst bed operates as a differential reactor, while the whole system gives an outlet concentration differing significantly from that of the feed. This significantly simplifies problems of chemical analysis. In practice, the recycle reactor operates differentially if the recycle ratio Fv.ret/Fv.f is larger than 25. The rate is then given by the overall rate ... 

Figure 7.10 Circular developuent with the point of solvent entry at the plate center (A). Anticircular developnent fron the outer circle towards the center (B). (Reproduced with penission from ret. 13. Copyright American chemical Society).

Figure 5. The integrated band intensity (1) and the band position (2) of linearly adsorbed CO are plotted as a function of potential in (a) 1 M HC104, (b) 1 M H2S04, and (c) 1 M HCL (Reprinted from ret 31. Copyright 1985 American Chemical Society.)...

Figure 6. The potential dependence of (1) the IR band center and (2) the integrated band intensity of adsorbed CN- on Au, and (3) the integrated band intensity of the [Ai CNy complex. (Reprinted from ret 25. Copyright 1988 American Chemical Society.)...

Fig. 36 Sensing mechanism of the TBA probe for the detection of Pb2+ and Hg2+ through enhanced RET-type quenching. (Reprinted with permission from [212]. Copyright 2009 American Chemical Society)...

Three of these experimental laser-based methodologies, LIF, REMPI, and RET, have been successfully applied to the study of the physical-chemical properties of chiral molecular clusters. 

Fig. 3 Relative dipole-bound anion formation rates in RET collisions between Rydberg Xe(nf) atoms with (a) adenine (circles) or imidazole (squares) molecules and (b) adenine-imidazole complex produced in a supersonic beam. Experimental data are fitted to curvecrossing model calculations which lead to the experimental determination of EAdS values, equal to 11 meV for adenine, 23 meV for imidazole and 54 meV for adenine-imidazole complex (reproduced by permission of the American Chemical Society).

Figure 5. (a) Structure of [Fe S.p Etpj. (Reproduced from ret 24. Copyright 1985 American Chemical Society.) (b) Structure of Fe (PEtj) Cly (Reproduced from ret 25. Copyright 1986 American Chemical Society.)... 

Linen is obtained from flax after a chemical treatment (retting). 

The role of size exclusion chromatography is the separation of rather complex coal liquids into simpler fractions. The retention volume can be used to help Identify the chemical structure where GC-MS is unable to identify its possible structure. For example biphenyl and dihydroacenaphthene have the same molecular formula as well as similar mass spectral fragmentation patterns. Coal liquids contain both species. The one which appears first (lower SEC retention volume) is biphenyl (GC ret. time = 17 min. in Figure 5-6). Dihydroacenaphthene appears later at longer SEC retention volume and is identified in Figure 5-12 at GC retention time of 13 minutes. The former has a longer structure compared to the latter. 

The electronic coupling between an initial (reactant) and a final (product) state plays a key role in many interesting chemical and biochemical photoinduced energy and electron transfer reactions. In excitation (or resonance) energy transfers (EET or RET) [1,2], the excitation energy from a donor system in an electronic excited state (D ) is transferred to a sensitizer (or acceptor) system (A). Alternatively, in photoinduced electron transfers (ET) [3,4], a donor (D) transfers an electron to an acceptor (A) after photoexcitation of one of the components (see Figure 3.50). 

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