Patch Testing with Propolis of Different Geographical Origins in a Baseline Series

The chemical composition of propolis varies with geographical origin; however, it is not known whether this affects the frequency of contact allergy to propolis. In order to study the frequency of contact allergy to propolis of different geographical origins and concomitant reactions, 1,470 consecutive patients with dermatitis from Denmark, Lithuania and Spain were patch tested with propolis from China, Lithuania, North America and Sweden, and with a baseline series. Patch test reactions to any type of propolis ranged from 1.3% to 5.8%. There were no statistically significant differences in the frequency of positive reactions between the 4 types of propolis in the respective countries. Testing with a single commercially available type of propolis detects only approximately half of propolis-allergic patients. In patients allergic to propolis, concomitant reactions to Myroxylon pereirae resin, colophonium and Fragrance mix I were common, ranging from 12.5% to 50.0%.

Monitoring of the State of the Environment in the Zone of Influence of the Landfill of Industrial and Domestic Waste by Bioindication Methods

The results of assessing the state of surface water bodies located in the zone of influence of the closed landfill of industrial and household waste "Shcherbinka" (Domodedovsky district of the Moscow region) are presented. The toxicity of river and waste waters of the landfill was determined by the biological effect on two species of higher plants – oats sowing (Avena sativa) and watercress (Lepidium sativum). As test reactions, the length of the roots of oat seedlings, the germination and length of seedlings of watercress seeds were used. It was found that wastewater from the surface and body of the landfill has a pronounced phytotoxic effect (52–98 %), which manifests itself in the suppression of all the assessed indicators. The high toxicity of river water in the place of discharge of leachate from the waste disposal facility was shown (the phytoeffect value reaches 37 %). As you move away from the source of pollution (when moving downstream of the river), mixing the leachate with river water reduces the concentration of chemicals in the waters to levels that are safe for plants. The values of the estimated indicators obtained during biotesting of river waters at a distance from the landfill are comparable with the control ones. The experiment revealed a similar sensitivity to toxicants of two plants selected as test objects.

Electron-rich triarylphosphines as nucleophilic catalysts for oxa-Michael reactions

Electron-rich triarylphosphines, namely 4-(methoxyphenyl)diphenylphosphine (MMTPP) and tris(4-trimethoxyphenyl)phosphine (TMTPP), outperform commonly used triphenylphosphine (TPP) in catalyzing oxa-Michael additions. A matrix consisting of three differently strong Michael acceptors and four alcohols of varying acidity was used to assess the activity of the three catalysts. All test reactions were performed with 1 mol % catalyst loading, under solvent-free conditions and at room temperature. The results reveal a decisive superiority of TMTPP for converting poor and intermediate Michael acceptors such as acrylamide and acrylonitrile and for converting less acidic alcohols like isopropanol. With stronger Michael acceptors and more acidic alcohols, the impact of the more electron-rich catalysts is less pronounced. The experimental activity trend was rationalized by calculating the Michael acceptor affinities of all phosphine–Michael acceptor combinations. Besides this parameter, the acidity of the alcohol has a strong impact on the reaction speed. The oxidation stability of the phosphines was also evaluated and the most electron-rich TMTPP was found to be only slightly more sensitive to oxidation than TPP. Finally, the catalysts were employed in the oxa-Michael polymerization of 2-hydroxyethyl acrylate. With TMTPP polymers characterized by number average molar masses of about 1200 g/mol at room temperature are accessible. Polymerizations carried out at 80 °C resulted in macromolecules containing a considerable share of Rauhut–Currier-type repeat units and consequently lower molar masses were obtained.