V-type complexes

In the context of this chapter, the use of thermoplastic starch in blends with thermoplastic resins is of the main interest. As shown in Table 16.11, several blends have been developed, e.g., with vinyl alcohol copolymers (EVAl), polyolefins, aliphatic polyesters such as poly-e-caprolactone (PCL) and its copolymers, or polymers of glycols (e.g., 1,4-butanediol) with succinic, sebacic, adipic, azelaic, decanoic or brassihc acids, PCL + PVC. Compatibilization is possible by amylose/EVAl V-type complexes, starch grafted polyesters, chain extenders like diisocyanates, epoxies, etc. [Bastioli et al., 1992, 1993]. 

The presence of compatibilizers between starch and aliphatic polyesters is preferred. Some examples are amylose/EVOH V-type complexes [92], and starch-grafted polyesters. The use of chain extenders such as diisocyanates and epoxides is preferred. Such materials are characterized by excellent compostability, excellent mechanical properties, and reduced sensitivity to water. 

Fourier transform infrared (FTIR) second-derivative spectra of thermoplastic starch and vinyl alcohol copolymer systems with droplet-like structure, in the range of starch ring vibrations between 960 and 920 cm , provide for an absorption peak at about 947 cm (Figure 2.7), as observed for amylose when complexed (V-type complex) by low-molecular-weight molecules such as butanol and fatty acids. 

The formation of complexes between starch and other polymers e.g. V-type complexes [50, 122]). 

Therefore, the absorption at 947 cm" does not correspond to crystalline or gelatinised amylose, bnt to a complexed one (V-type complex), as in the presence of low molecular weight molecules such as butanol and fatty acids [4, 134]. Starch-based materials with an amylose content close to zero, even in the presence of vinyl alcohol copolymers, do not show any peak at 947 cm demonstrating that vinyl alcohol copolymers, as well as butanol, leave the amylopectin conformation unchanged. 

B type (characteristic of potato) C type (characteristic of cassava) V type (complex with other molecules)... 

The rates of oxidation of V by complexes of the type Co(NH3)sX, where X = H2O, NH3 and Cl , have been examined by Zwickel and Taube in H2O and in D2O solution. These workers have compared the results on such systems with data on the Cr +Co(NH3)6 reaction in H2O and D2O. The product unlike Cr, is substitution-labile. Consequently, a different approach is necessary for oxidations than is customary for Cr oxidations. The specific rate coefficients for Co(NH3)g and Co(NH3)6 " + Cr vary with Cl concentration according to... 

These oxidations have attracted wide interest and both specialised and comparative studies have been published. The rate laws which are summarised in Table 14 are not distinctive although the acidity dependence of the V(V) oxidations of some substrates suggests by analogy that a pinacol-type of oxidation may occur cf. V(V)-pinacol complexes, p. 388), viz. 

Based on the above observation, it can conceivably be concluded that the presence of Fe-WEHS-type complexes can be of relevance to the Fe nutrition of both strategy I and strategy II plants (Fig. 1). In the case of strategy I plants, an effect on the mechanisms of active proton extrusion should also be considered (see Sect. V). 

In thiosalen-type complexes the Ni11 ion usually has a four-coordinate square planar geometry.1360,1361 Complex [Ni(510)] shows a quasi-reversible reduction at —1.36 V and an irreversible... 

Silver(I) complexes with other O-based ligands have been reported. /V,/V-Dialkylcarbamato complexes of the type [Ag(02CNR2)] have been only recently prepared according to Equation (8) ... 

Simple transition metal halides react cleanly with alkali metal boratabenzenes. In this way sandwich-type complexes 32 of V (27), Cr (64), Fe (58), Ru (61), and Os (61) have been made. The corresponding nickel complexes seem to be nonexistent, quite in contrast to NiCp2 in attempted preparations, mixtures of diamagnetic C—C linked dimers were obtained (29). In the manganese case, high sensitivity to air and water has precluded preparative success until now. Some organometallic halides have added further variations to the main theme. The complexes 33 of Rh and 34 of Pt were obtained from [(COD)RhCl]2 and [Me3PtI]4, respectively (61). 

F-ATPases (including the H+- or Na+-translocating subfamilies F-type, V-type and A-type ATPase) are found in eukaryotic mitochondria and chloroplasts, in bacteria and in Archaea. As multi-subunit complexes with three to 13 dissimilar subunits, they are embedded in the membrane and involved in primary energy conversion. Although extensively studied at the molecular level, the F-ATPases will not be discussed here in detail, since their main function is not the uptake of nutrients but the synthesis of ATP ( ATP synthase ) [127-130]. For example, synthesis of ATP is mediated by bacterial F-type ATPases when protons flow through the complex down the proton electrochemical gradient. Operating in the opposite direction, the ATPases pump 3 4 H+ and/or 3Na+ out of the cell per ATP hydrolysed. 

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