Structural degradation

The first paper on the bioactive polysaccharides from Glycyrrhiza uralensis roots was published in 1996 by Kiyohara et al. [57]. They isolated a pectic type polymer with anti-complementary and mitogenic activity that was an acidic pectin, possibly containing rhamnogalacturonan type I as part of the total structure. Degradation of the uronic acid part of the molecule decreased both types of bio activities. The neutral oligosaccharide chains were shown to retain some of the activities of the native polymer, but it was suggested that they should be attached to the acidic core to retain maximum activity. 

The powder XRD patterns of calcined and ion-exchanged MAPO-36 are shown in Fig.l. The XRD patterns of calcined MAPO-36 coincided with already reported data [7]. The XRD patterns of ion-exchanged MAPO-36 revealed absence of structural degradation. Further, there are no patterns corresponding to non-framework metal oxide. 

Churchman GJ, Gates WP, Theng BKG, Yuan G (2006) Clays and clay minerals for pollution control. In Bergaya F, Theng BKG, Lagaly G (eds) Handbook of clay science. Elsevier, Amsterdam, pp 625-676 Cicel B, Kranz G (1981) Mechanism of monmorillonite structure degradation by percussive grinding. Clay Miner 16 151-162... 

According to this method, nano-structured materials (even in commercial quantities) are produced by structural degradation of coarser-grained structures by the application of high-mechanical energy. 

A poorly balanced water distribution in the fuel cell can severely impair its performance and cause long-term effects due to structural degradation. If PEMs or CLs are too dry, proton conductivity will be poor, potentially leading to excessive joule heating, which could affect the structural integrity of the cell. Too much water in diffusion media (CLs and GDLs) blocks the gaseous supply of reactants. As these examples show, all processes in PEECs are linked to water distribution and the balance of water fluxes. 

Hence, the presence of trace impurities, which either pre-exist in pristine electrode and bulk electrolyte or are introduced during the handling of the sample, could profoundly affect the spectroscopic images obtained after or during certain electrochemical experiments. This complication due to the impurities is especially serious when ex situ analytic means were employed, with moisture as the main perpetrator. For cathode/electrolyte interfaces, an additional complication comes from the structural degradation of the active mass, especially when over-delithiation occurs, wherein the decomposition of electrolyte components is so closely entangled with the phase transition of the active mass that differentiation is impossible. In such cases, caution should always be exercised when interpreting the conclusions presented. 

Coatings based on these different crosslinkers have substantially different cure kinetics, network structure, and durability. Formation and degradation of crosslink structure in urethane and melamine crossllnked coatings are compared in this paper. Key differences in cure chemistry and kinetics which result differences in coating performance are identified. The chemistries of network structure degradation on exposure to UV light and water are discussed in terms of their effect on ultimate durability. 

Results on epoxidation of cyclohexene with H2O2 with freshly prepared catalysts are given in Table 2. With Mo blue, exchanged on Mg,Al-LDH, the olefin conversion is low, even if all peroxide is consumed within 4 h. Upon addition of the H2O2 to the reaction mixture, the suspended catalyst has the yellow hue of the Movl form of the isopolyacid. However, the suspension soon turns brick red. This color is characteristic for tetraperoxomolybdate Mo(02)42 [17], This indicates that the isopolyacid structure degrades rapidly, with formation of Mo monomers. Peroxo complexes such as Mo(0 )42 or particularly MoO(C>2)32 are known to decompose with formation of 02 the overall process is a decomposition of two molecules of H2O2 into water and C>2 [18] ... 

It was mentioned earlier that catalytic hydrogenation of protoporphyrin-IX (19) produces mesoporphyrin-IX (46), and that this type of vinyl modification has been used in structural degradation methods. The vinyl group can also be modified for degradative purposes by addition of diazoacetic ester, which produces the corresponding cyclopropane derivatives... 

Laufer S. Role of eicosanoids in structural degradation in osteoarthritis. Curr Opin Rheumatol. 2003 15 623-627. 

Cantier, J.M., J. Bastide, and C. Coste. 1986. Structure-degradability relationships for propyzamide analogues in soils. Pestic. Sci. 17 235-241... 

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