Formaldehyde cross-linking, effect

It has also been found that there can be interactions between hydrolytic degradation and photochemical degradation. Especially in the case of melamine-formaldehyde cross-linked systems, photochemical effects on hydrolysis have been observed. 

In summary, formalin-treated does not significantly perturb the native structure of RNase A at room temperature. It also serves to stabilize the protein against the denaturing effects of heating as revealed by the increase in the denaturation temperature of the protein. However, formalin-treatment does not stabilize RNase A sufficiently to prevent the thermal denaturation of the protein at temperatures used in heat-induced AR methods as shown by both DSC and CD spectropolarimetry. This denaturation likely arrises from the heat-induced reversal of formaldehyde cross-links and adducts, as shown in Figure 15.4 of Section 15.4. Further, cooling formalin-treated RNase A that had been heated to 95°C for 10 min does not result in the restoration of the native structure of the protein, particularly in regard to protein tertiary structure. 

EFFECT OF ETHANOL DEHYDRATION ON THE REVERSAL OF FORMALDEHYDE CROSS-LINKS... 

Fowler CB, O Leary TJ, Mason JT Modeling formalin fixation and histological processing with ribonuclease A effects of ethanol dehydration on reversal of formaldehyde cross-links. Lab. Invest. 2008 88 785-791. 

Yasuda, R. and Minato, K. (1995). Chemical modification of wood by non-formaldehyde cross-linking agents. Part 3. Mechanism of dimensional stabilization by glyoxal treatment and effect of the addition of glycol. Wood Science and Technology, 29(4), 243-251. 

Melamine/formaldehydes cross-link with epoxy resins to give low-colour coatings with good physical properties, chemical resistance, and no effect on... 

The effects of diffusion control on the rate of radiation-initiated graft polymerization of cellulose have been studied theoretically. The effects of such variables as the initiator concentration, temperature, and monomer polymer ratio on the graft copolymerization of acrylamide and 0-methylcellulose have been investigated. The thermal properties and behaviour of graft copolymers of formaldehyde-cross-linked 0-cyanoethylcellulose and acrylates have been studied. Copolymerization of periodate-oxidized cellulose (aldehydocellulose) with glycidyl methacrylate in the presence of an enzyme e. peroxidase) afforded a means of immobilizing the enzyme without loss of activity. ... 

In this case, the components are mixed, the pH adjusted to about 6.0 with sodium hydroxide, and the solution appHed to the textile via a pad-dry-cure treatment. The combination of urea and formaldehyde given off from the THPC further strengthens the polymer and causes a limited amount of cross-linking to the fabric. The Na2HP04 not only acts as a catalyst, but also as an additional buffer for the system. Other weak bases also have been found to be effective. The presence of urea in any flame-retardant finish tends to reduce the amount of formaldehyde released during finishing. 

Although formaldehyde penetrates very quickly, its protein cross-linking fixative effects are not as immediate. Modifications to this and improvements on the model used originally in studies by Baker et al.,7 Fox et al.,8 and Helander9 have demonstrated that in tissue and in these more complex models, the penetration and therefore Medawar s constant for formaldehyde is not as great as 5.5 and is probably more like 3.6.7... 

Finally temperature and tissue type do have an effect on the penetration and fixation. This, combined with a failure to appreciate protein cross-linking time or actual fixation time required for formaldehyde, is probably the main reason for intra- and interlaboratory variation. 

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