Effect of formaldehyde

As with resoles, the central issue in design of novolacs is molecular weight. The effects of formaldehyde-to-phenol molar ratio and formaldehyde conversion on molecular weight of novolacs has been well studied and reported [192,193]. The effects of molecular weight on most of the important properties are also available [193]. These include Tg, melt viscosity, gel time, hot-plate flow, glass-plate flow. 

Note The dipping reagent is to be preferred because of the strongly irritating effects of formaldehyde on the respiratory tract. Detection limits of ca. 10—40 ng have been reported for alkaloids [4] and 50 ng — 1 pg for -blockers [2, 3]. 

Figure 4 Effect of formaldehyde content on the capacity of cationic resins.

Different effects of formaldehyde on the hydrolysis of urea are reported. On the one hand, Garrido and colleagues,3 applying anoxic conditions, observed that an inhibitory effect started at 50 mg/L formaldehyde and the levels of inhibition were 50% and 90% for concentrations of formaldehyde of 100 mg/L and 300 mg/L, respectively. Similar effects were found by Campos and colleagues,33 working with an anoxic USB, who observed that formaldehyde concentrations in the reactor of 250 to 300 mg/L caused an inhibition of around 53%. This inhibition on the ureolytic activity was also reported by Walker.36 On the other hand, Eiroa and colleagues37 carried out batch assays at different initial urea concentrations from 90 to 370mg/L N-urea in the presence of 430 mg/L formaldehyde. They observed that a complete hydrolysis was achieved and initial urea hydrolysis rates remained constant. 

Auerbach C, Moutschen-Dahmen M, Moutschen J. Genetic and cytogenetical effects of formaldehyde and related compounds. Mutat. Res. 1977 39 317-362. 

Mason JT, O Leary TJ. Effects of formaldehyde fixation on protein secondary structure a calorimetric and infrared spectroscopic investigation. J. Histochem. Cytochem. 1991 39 225-229. 

Effect of Formaldehyde Fixation on Antigen-Antibody Binding... 

Its mechanism of activation is shown in Fig. 9.7,a enzymatic hydrolysis produced 3-(hydroxymethyl)phenytoin, which then broke down to phenytoin and formaldehyde. The potential for unwanted effects of formaldehyde should not be forgotten. 

Stevens, M. and Parameswaran, N. (1981a). Effect of formaldehyde-acid catalysed reactions on wood ultrastructure. Wood Science and Technology, 15(4), 287-300. 

Tarkow, H. and Stamm, A.J. (1953). Effect of formaldehyde treatments upon the dimensional stailization of wood. Journal of the Forest Products Research Society, 3(2), 33-37. 

KuUe, T. J., and G. P. Cooper. Effects of formaldehyde and ozone on tlie trigeminal nasal sensory system. Arch. Environ. Health 30 237-243, 1975. 

The exact mechanism by which HIER works is unknown. It is thought to reverse the masking effects of formaldehyde fixation and routine tissue processing. Hydrolytic-proteolytic cleavage of formaldehyde-related crosslinks, unfolding of inner epitopes, as well as the extraction of calcium ions from coordination complexes with proteins are among the hypothesized mechanisms (13-15). 

Formaldehyde is one of the most common causes of occupational skin disease the major effects of formaldehyde on the skin are irritant dermatitis and allergic contact dermatitis. Irritant dermatitis results from direct injury to the skin and is characterized by redness and thickening of the affected areas. In more severe cases there may be blistering, scaling, and the formation of fissures. 

Horvath EP et al Effects of formaldehyde on the mucous membranes and lungs. JAMA 259 701-707, 1988... 

Saladino, A.J., Willey, J.C., Lechner, J.F., Grafstrom, R.C., LaVeck, M. Harris, C.C. (1985) Effects of formaldehyde, acetaldehyde, benzoyl peroxide, and hydrogen peroxide on cultured normal human bronchial epithelial cells. Cancer Res., 45, 2522-2526... 

An extensive study of the effects of formaldehyde in milk lipase inhibition showed that formaldehyde acts as a competitive inhibitor and, under the proper conditions, selectively inhibits the lipases of raw skim milk (Schwartz et al. 1956A). This study showed that the inhibitory effect of formaldehyde was dependent on such factors as pH, time of addition of the inhibitor, length of the incubation period, concentration... 

Cullis and Hinshelwood (13) noted that their spectroscopically pure hexane contained an impurity. With pure a-hexane the concentration of formaldehyde remained constant during the induction period, but the inhibiting effect of formaldehyde was still observed. 

Table II. Effect of Formaldehyde and Acetaldehyde on Induction Period of Propylene...

Table IV. Effect of Formaldehyde on Oxidation of Hydrocarbons and Allied...

The low-temperature oxidation represents a complex system and can be better interpreted when the elementary reactions are firmly established. We arc inclined to assign formaldehyde only a minor role in the low-temperature regime. Further experimental work is required to clarify the interactions between formaldehyde and peroxides, the radical-induced formaldehyde oxidation, and the effect of formaldehyde addition in the low-temperature hydrocarbon-oxygen systems. It has been established that mercury vapor is effective for the destruction of peroxides. Mercury vapor addition to systems in the cool-flame zone would perhaps be of value in assessing not only the role of peroxides, but also that of formaldehyde in this interesting region. 

The action of methenamine mandelate or hippurate is nonspecific against many different microorganisms and consists of the simultaneous effects of formaldehyde and acidity. Microorganisms such as proteus that make a strongly alkaline urine through release of ammonia... 

The chemistry of the effect of formaldehyde in the tanning process probably is related closely to its action in the production of toxoids (6). This procedure was developed in the first part of this century mainly by trial and error and still thrives today. Toxins are treated with formaldehyde for several weeks at temperatures close to 40°C. This results in the toxin being changed in such a manner that it retains its capacity to elicit an immune response when injected into an animal or person but it lacks the capacity for the specific and damaging attack that is associated with the native toxin. Imprecise as this procedure seems today, the satisfactory results obtained through strict quality control have resulted in its continuing use and the production of many millions of doses of life-saving vaccines. However, more specific modifications should be available for such purposes from current research. 

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