Cholic acid, deoxycholic acid, chenodeoxycholic acid, and ursodeoxycholic acid were purified by a foam fractionation method. Using thermogravimetric analysis, the attached water molecule was found to be completely removed from solids of the latter three at 100°C, while cholic acid still had one water molecule of crystallization per two cholic acid molecules at that temperature. The acidity cons...

We have studied the effect of a prostaglandin E2 analogue (enprostil), on intragastric acidity, gastric acid and pepsin outputs during a 24 hour period in nine patients with duodenal ulcer in remission. Enprostil 35 micrograms bd dose inhibited 24 hour intragastric acidity by 38% and a 70 micrograms nocturnal dose by 33%. Decrease in nocturnal pepsin secretion was both volume and concentration ...

Oxidative damage to DNA yields guanine radical cations. Their gas-phase IR spectroscopic signature and acidity have been modelled by the radical cation of 9-methylguanine. Comparisons with quantum chemistry calculations suggest that radical cation formation produces the ground-state keto tautomer, which has an N-H acidity enhanced by ~470 kJ mol(-1).

Understanding the nature of interaction between metal nanoparticles and biomolecules such as amino acids is important in the development and design of biosensors. In this paper, binding of M(3) clusters (M = Au, Ag and Cu) with neutral and anionic forms of histidine amino acid was studied using density functional theory (DFT-B3LYP). It was found that the interaction of histidine with M(3) clust...

Hybrid quantum mechanics:molecular mechanics (QM/MM) calculations of absolute deprotonation energies are performed with periodic boundary conditions for Brønsted sites of aluminosilicate bilayers with various Al/Si ratios (two-dimensional zeolite). The supercell method is applied and density functional theory is used. Much lower values are obtained (1042, 1069 and 1091 kJ mol(-1) for Al/Si = 1/...

Our purpose is to understand the mechanism through which pH affects the competition between base-induced elimination and substitution. To this end, we have quantum chemically investigated the competition between elimination and substitution pathways in H2O+C2H5OH2 (+) and OH(-)+C2H5OH, that is, two related model systems that represent, in a generic manner, the same reaction under acidic and bas...

New solid strong bases were fabricated at room temperature by grafting lithium-containing molecular precursors onto β-cyclodextrin. The solid bases show strong basicity with a molecular-level dispersion of lithium sites, which are highly active in transesterification reactions and impossible to realize through the traditional high-temperature method.

A redox strategy was designed to generate strong basicity on mesoporous silica by using the redox interaction of a precursor with methanol vapor. The formation of strongly basic sites was realized at 400 °C, which breaks the tradition of thermally induced decomposition that usually requires much higher temperatures (>600 °C).

The effect of fertilizer rate on fruit quality parameters in the black chokeberry (Aronia melanocarpa [Michx] Ell.) cv. `Viking' was studied over three years. A combined N±P±K fertilizer was applied in different rates. Plant height, yield, berry weight, anthocyanin content, content of brown compounds, content of soluble solids, anthocyanin composition and total acidity were recorded for the dif...

Our previous finding of a fractal pattern for gastric pH and esophageal pH plus the statistical association of sequential pH values for up to 2 h led to our hypothesis that the fractal pattern encodes information regarding gastric acidity and that depending on the value of gastric acidity, the esophagus can signal the stomach to alter gastric acidity by influencing gastric secretion of acid or ...