ABSTRACT
An organic droplet containing thymol acetate (TA) floating on a sodium dodecyl sulfate aqueous phase was examined to develop a novel self-propelled object based on reaction kinetics. Two types of oscillatory motion, without back-and-forth motion (Osc I) and with back-and-forth motion (Osc II), were observed by varying the pH of the aqueous phase. The oscillation frequency reached its maximum at pH 9.6, coinciding with the occurrence of Osc II. The kinetics of the hydrolysis of TA as a reactant and the acid-base equilibrium between thymol (TOH) and the thymolate ion (TO-) as products were evaluated experimentally. The driving force of motion was discussed on the basis of the interfacial tension. The pH dependence of the oscillation frequency and the selection of Osc I or II were attributed to the equilibrium between the TOH and TO-. These results highlight the possibility of designing self-propulsion systems by considering reaction kinetics and chemical properties.
ABSTRACT
BACKGROUND: It remains controversial whether gastric atrophy is reversible after Helicobacter pylori eradication therapy. AIM: To clarify whether gastric atrophy improves after H. pylori eradication therapy using a histologic approach. METHODS: Subjects were 87 H. pylori infection-cured patients (treatment group) and 29 continuously H. pylori-infected patients (control group). The subjects in the treatment and control groups were followed for 10-49 months (mean, 22 months) and 11-50 months (mean, 22 months), respectively. Biopsy specimens were obtained from the greater curvature of the antrum and corpus at the beginning and end of the observation period; histologic analyses of these specimens were performed for detection of activity, inflammation, atrophy, and intestinal metaplasia. Results were scored without any clinical information according to the Sydney system. RESULTS: In the treatment group, the histologic score for atrophy was improved in the corpus but not in the antrum. Intestinal metaplasia was not improved in either the antrum or the corpus. There were no significant differences during the follow-up in gastric atrophy and intestinal metaplasia in the control group. CONCLUSION: Gastric atrophy was improved in the corpus approximately 2 years after H. pylori eradication therapy.
