Electron stimulated desorption of anions and cations from condensed allyl glycidyl ether.

We report measurements of the electron stimulated desorption (ESD) of anions and cations from thin films of allyl glycidyl ether (AGE), formed by condensation onto multilayer Kr and Pt substrates using a high sensitivity time of flight mass analyser. Measurements were performed as a function of film thickness, incident electron energy (E(i)) and effective incident current. Below incident electron energies of 20 eV the desorption of anions is dominated by the process of dissociative electron attachment (DEA) via several transient negative ions at E(i) between 5.5 and 16.5 eV. Comparisons between measurements for AGE and ethyl oxirane show that the ESD of anions is essentially that of the glycidyl (epoxide) ring, though DEA occurring at the ether, within the linear part of the AGE molecule is also observed. Cation yields are dominated by the desorption of small fragments formed via scission of the same ether bond.

The effect of non-surgical periodontal and adjunctive minocycline-HCL treatments on the activity of salivary proteases.

The purpose of this investigation was to evaluate the effect of non-surgical periodontal treatment and adjunctive systemic minocycline therapy on the level of neutral protease activity in whole saliva of adults with periodontitis. A test group of 21 adult patients with moderate to severe periodontitis was compared to a control group of 5 adults with healthy periodontium. Four test groups were examined: 1) scaling and root planing (SRP), probing depth = 4 to 5 mm; 2) SRP, PD > or = 6 mm; 3) SRP and adjunctive systemic minocycline therapy, PD = 4 to 5 mm; 4) SRP and adjunctive systemic minocycline therapy, PD > or = 6 mm. Clinical parameters and levels of neutral protease in whole saliva were assessed at baseline and on the sixth week after the non-surgical periodontal treatment. Neutral protease activity was measured by spectrofluorimetric method. Statistical tests of Mann-Whitney and Spearman Rank correlation coefficient were used in the evaluation of the mean values of measurements. The mean values of protease activity were significantly higher in the test groups than in the control group at baseline. Six weeks after non-surgical therapy, patients with 4 to 5 mm probing depth had approximate values of protease activity comparable to the control group. Hence it can be argued that these patients did not need minocycline HCL as an adjunctive therapy. However, non-surgical therapy had limited effects on both clinical parameters and enzyme activities for subjects with > or = 6 mm probing depth; on the other hand, gingival inflammation and enzyme activities were reduced significantly by the usage of minocycline as adjunctive therapy in these patients. According to our results, neutral protease activity in saliva is related to probing depth and gingival bleeding index, and not related to age and epithelial cell number. For these reasons, systemic minocycline therapy might be useful as an adjunct to non-surgical therapy in the presence of deep pockets, especially for reinfected cases. Further investigations are needed to confirm this suggestion.

Determination of the relative impact of chromatographic conditions and solute structures on the retention behaviour of non-ionic surfactants in RP-HPLC.

The retention behaviour of non-ionic surfactants containing different hydrophobic moiety and various lengths of polar ethylene oxide chain was studied on RP-8 and RP-18 columns using methanol and acetonitrile as organic modifiers. The relative impact of the chromatographic conditions on the retention strength was determined using stepwise regression analysis. Non-ionic surfactants can be separated according to the character of the hydrophobic moiety, but not according to the length of the polar ethylene oxide chain. Calculations proved that the organic modifier exerted the highest impact on the retention; the effect of the number of carbon atoms in the hydrophobic moiety, column temperature and the length of the hydrophobic ligand on the surface of silica support are of secondary importance.