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The present study investigated the possibility of using an electrolytic cell to prevent nonenzymatic browning in lemon juice products. A single-strength, a double strength and a triple-strength lemon juice were subjected to four different current densities (0.116, 0.231, 0.463 and 0.926 A/m$ sp2)$ for 30 minutes using an electrolytic cell. Dissolved oxygen level, conductivity, redox potential, pH in juices and the voltage applied to the electrodes required to maintain constant current density through the cell were monitored. Juice samples were taken at 0, 5, 15 and 30 minutes and then stored for one month at 30$ sp circ$C. / After one month of storage, juice samples were assessed for browning and quality alteration. The chemical indices used were the browning index and concentrations in furfural and 5-hydroxymethylfurfural (HMF). Although redox potentials and concentrations in dissolved oxygen were significantly reduced by the electrolytic cell treatment, none of the electrochemical treatments significantly retarded detrimental reactions in juices over the storage period. Initial levels in dissolved oxygen and redox potential do not seem to have any significant effect on browning or chemical quality deterioration in lemon juices. Thus, the present study suggests that nonenzymatic browning in lemon juice products may be due to factors other than oxidative reactions.

<p>Includes Bibliographical references (leaves 83- 94).Forty-three male athymic nude mice were implanted with human vaginal mucosal cysts under general anaesthesia with Ketamine [25mg/kg] and Medetomidine [0.5mg/kg]. Cysts in 37 mice were recovered after 9 weeks of growth. twenty three cyst linings had retained the original structure of the vaginal epithelium. No marked deifference was present between the thickness of 9 week old linings and donor vaginal epithelium. The contaminants isolated from the skin of mice before implantation were mainly normal commercals of healthy experimental animals. There was no distinct difference in the number of cases with intact cyst formation between the terramycin/vitamin cocktaik group. The frequency of poor wound healing and/ or murine epidermis ingrowth was three times higher in animals stitched with silk sutures that in those cases where nylon sutures were used.</p>

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The synthesis of methyl 3,6-dimethylpyridine-2-carboxylate (192) by the Diels-Alder addition of 3-butene-2-one dimethylhydrazone (190) and methyl-2-butynoate (16) is described. The structure of 192 was confirmed by the synthesis of methyl 2,6-dimethylpyridine-3-carboxylate (195), the opposite regioisomer.The synthesis of methyl 3,5-dimethylpyridine-2-carboxylate (199) from [4+2] cycloaddition of 2-methyl-2-propenal dimethylhydrazone (171) and 16 is described. In addition to producing a small amount of 199 directly, the reaction produced an intermediate of possible structure 198 which yielded 199 on catalytic dehydrogenation.On prolonged heating, 2-acetyl-5-methylpyridine (200) was produced by the reaction of diene 171 with methyl vinyl ketone (176).The preparation of 2-cyan-5-methylpyridine (201) from the tetrahydropyridine derivative 175 via catalytic dehydrogenation is described.The synthesis of 5,7-dioxo-3-methyl-6-phenyl-1,1.,5,6,7-pentahydropyrroloC3,1.-b] pyridine (202) through the Diels-Alder addition of diene 171 and N-phenylmaleimide (149) is described. Also reported is the preparation of 5,7-dioxo-3-methyl-6-phenyl-3,5,6-trihydropyrrolo [3,1+-b]pyridine (203) via dehydrogenation of 202. / Department of Chemistry

The duration of the post reinforcement pause was measured for three white rats on fixed ratio schedules of reinforcement ranging from 26 to 120. The post reinforcement pause consistently increased as the ratio requirement increased for all three subjects. The data failed to show one function (power, logarithmic, or linear) as significantly more useful than the other two in describing the relationship between systematically increased fixed ratios and the respective post reinforcement pause for each ratio. Furthermore, there was no consistent relationship between the response rate and the fixed ratio requirement.