An NMR titration method has been used to simultaneously measure the acid dissociation constant (pKa) and the intramolecular NHO prototropic constant ΔKNHO on a set of Schiff bases. The model compounds were synthesized from benzylamine and substituted ortho-hydroxyaldehydes, appropriately substituted with electron-donating and electron-withdrawing groups to modulate the acidity of the intramolec...

Soil acidity can affect plant growth directly and indirectly by affecting the plantavailability of nutrients, levels of phytotoxic elements, and microbial activity. Soils may become acidic in the long term as a result of several natural processes. In the short term, however, soil acidity develops mainly due to application of N fertilizers or manure, primarily those having high concentrations of...

The influence of acidity on the growth of plants in water-culture has been studied by investigators with varying results. Many have reported a beneficial effect of moderate acidity; whereas others have succeeded in demonstrating equally good growth in solutions of widely different hydrogen-ion concentration. Citations to the literature can be found in a paper by the writer (5) dealing with the ...

Recent evidences suggest that the acidic microenvironment might facilitate epithelial mesenchymal transition (EMT) of tumor cells, while the effects of acidity on EMT of pancreatic cancer (PC) remain undefined. The present study demonstrated that acidity suppressed miR-652 expression, which further promoted EMT process by absenting inhibition on the transcriptional factor ZEB1 expression. At fi...

Hollander's insulin test was evaluated by performing successively partial denervation of the parietal cell area, highly selective, selective, and truncal vagotomy operations on three dogs. The rise in acidity, the timing of the highest rise in acidity, and the rise in acid output were examined. The mean rise in acidity (m-equiv/l) before vagotomy (106 +/- SE11, 120 +/- 23, 60 +/- 16) did not di...

Topographic Effects on Stormflow Acidity David Wolock 1 This paper describes the theoretical and observed effects of topography onstormflow acidity in upland, forested watersheds. The theoretical effects were determined by a sensitivity analysis using the hydrologic model TOPMODEL. The observed effects were determined by an analysis of topographic and stormflow acidity data collected from eight...

The acidity constants of 4-(2-pyridylazo)resorcinol (PAR, Scheme 1) in binary mixtures of methanol–water at 25 ◦C and an ionic strength of 0.1 M have been determined spectrophotometrically. DATa ANalysis (DATAN) program applied for determination of acidity constants. As percent of methanol increases in solvent mixtures the pKa constants also increased. There is linear relationship between acidi...

Absolute rate constants for hydrogen abstraction from 4-methylphenol (para-cresol) by the lowest triplet states of 24 aromatic ketones have been determined in acetonitrile solution at 23 degrees C, and the results combined with previously reported data for roughly a dozen other compounds under identical conditions. The ketones studied include various ring-substituted benzophenones and acetophen...

accumulation, 71, 110, 111 non-ideal, 81 agarose, 33, 35, 44 pore size, 59 alkalinity, 35, 176, 183 aluminium, 44, 67, 176, 238 ammonia, 35, 176 ammonium persulphate, 33, 266 analytical techniques, 285 colorimetry, 181–182 computer imaging densitometry (CID), 181–182, 185, 202, 285 hyperspectral imaging, 182 laser ablation – ICPMS, 185–188, 285 PIXE, 175, 176 antimony, 44, 67, 135 area of windo...

We herein report on the effect that water molecules, present as impurities, in the vicinity of an ionic liquid model structure, may induce on the Lewis acidity/basicity patterns normally observed in these materials. Depending on the position and orientation of water, the Lewis acidity/basicity pattern changes from "normal distribution" (i.e., the basicity located at the anion moiety and the aci...