Synthesis of photodegradable polymers by SH-En polyaddition

Summary The polyaddition reaction of the Michael donor 1.2-bis(2-mercaptoethoxy)ethane (Bis-SH) 2 as dithiol to various Michael acceptors such as divinyl sulfone (DVS) 1, N,N-bismaleimido-4,4-diphenylmethane 3, 4,4-(N-maleimido)diphenyliodoniumchloride 4 and diallyl succinate 5 in the presence of tributylamine is described. Polymers were characterized by NMR-spectroscopy, elemental analysis, DSC and TG-analysis. In particular we synthesized a photosensitive polymer with 4,4-(N-maleimido)diphenyliodonium chloride as comonomer, which eliminated analytical amounts of HCl during irradiation.     

Economic analysis of small wind-energy conversion systems

The financial costs of obtaining electricity from small wind-energy conversion systems are calculated and compared with the cost of electricity from traditional utility companies. A 3 kW rated wind electric system for residential use is examined. The amount of energy from this system is estimated by using a computer-operated simulation model which incorporates wind speeds, residential electricity demands and parameters from the generator, inverter and storage components. Variations in electricity costs as a function of available wind energy, residential consumption patterns and system components and costs are examined. The cost of electricity from small wind-energy conversion systems has considerable variations under differing assumptions or parameters but may, in some cases, be competitive with utility company costs.     

Tunnelling in the Federal Republic of Germany: Analysis for 1985–1986

The author presents the results of a study of tunnelling activity in the Federal Republic of Germany for the years 1985–1986, 1984–1985 and 1983–1984. The study compares six categories of tunnels for each year: underground and commuter railway tunnels; federal railway/long-distance railway tunnels; urban and highway road tunnels; water and other supply tunnels; waste tunnels; and miscellaneous tunnels. Tables and graphs are used to compare overall tunnel drivage length, excavated diameter, means of construction, e.g. mining, cut-and-cover, and placing of contracts as related to excavated volume and drivage length. The author notes that tunnels being constructed as part of the German Federal Railway's program to develop high-speed routes account for the great majority of non-urban traffic tunnel constructions, and that this trend will continue in years to come.