We have used microcalorimetry to measure the differential heats of adsorption of both a series of alkylamines and a series of substituted pyridines in H-ZSM-5 and H-Mordenite. With few exceptions, the differential heats are approximately constant to coverages close to the expected Brønsted site concentration. Both zeolites show good correlations between the average differential heats of adsorption and the gas-phase proton affinities of the basic adsorbates. Slopes of the correlation lines for the two zeolites are similar; the intercepts differ by about 15 kJ/mol. We use this data set to demonstrate that a self-consistent, quantitative Brønsted acidity scale for solid acids cannot be obtained from heats of adsorption of ammonia or pyridine or any other single reference base. However, the correlation between heats of adsorption and gas-phase proton affinities does provide a useful starting point for a more complete description of the thermochemistry of proton transfer reactions in zeolites. Deviations from the correlation curves for specific zeolite/adsorbate pairs can be used to infer how the strengths of Coulombic, hydrogen-bonding, or van der Waals interactions change with structure of either the zeolite acid or the adsorbate base.

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Gastroesophageal reflux disease (GERD) is one of the most common diseases affecting patients worldwide, but its risk factors and causes are not clearly known. The aim of this study was to investigate the effect of coffee intake on GERD by a meta-analysis. We searched online published research databases such as PubMed, EMBASE, and Cochrane Library for studies that were published up to December 2012. These publications were reviewed by two independent authors, and studies that fulfilled the criteria were selected. Whenever there was a disagreement between the authors, a consensus was reached by discussion. Fifteen case-control studies were included in the final analysis. A meta-analysis showed that there was no significant association between coffee intake and GERD. The odds ratio was 1.06 (95% confidence interval, 0.94-1.19). In subgroup analyses in which the groups were subdivided based on the definition of GERD (diagnosed by endoscopy or by symptoms alone), only the endoscopy group showed a significantly higher odds ratio. In subgroup analyses in which the groups were subdivided based on the amount of coffee intake, quality of study, and assessment of exposure, there was no significant association between coffee intake and GERD.