Poly(vinyl pyridine)s: A Versatile Polymer in Catalysis

The PVP and its derivatives have been broadly applied in polymers, organic syntheses, and catalysis processes. The crosslinked PVP is a well-known polymer support for numerous reagents and catalysts. Cross-linked PVPs are commercially available polymers and have attracted much attention over the past due to their interesting properties such as the facile functionalization, high accessibility of functional groups, being nonhygroscopic, easy to prepare, easy filtration, and swelling in many organic solvents. A brief explanation of the reported applications of PVPs in different fields followed by the discussion on the implementation of methodologies for catalytic efficiency of PVP-based reagents in the organic synthesis is included. The aim is to summarize the literature under a few catalytic categories and to present each as a short scheme involving reaction conditions. In the text, discussions on the synthesis and the structural determination of some typical polymeric reagents are presented, and the mechanisms of some organic reactions are given. Where appropriate, advantages of reagents in comparison with the previous reports are presented. This review does not include patent literature.

A ventilation system in the Portuguese mining company Almina

In order to work in a mine, two main requirements have to be met - roof and ground support and ventilation support. Roof and ground support is important because in case of an accident, workers can, without problems, evacuate the mine. However, besides roof and ground support, in order to fulfill normal working conditions inside the mine, a ventilation system is a valuable and key part of the working process. This paper represents the ventilation system in the Portuguese mining company Almina. It encompasses a ventilation system in the underground and on the surface. The main problems of a ventilation system are discussed, as well as a short scheme of fresh air inhalation and stale air exhalation outside the mine. The result of the paper was to figure out how the ventilation system operates in practice. The aim of the paper was to present a real ventilation system by taking into consideration the fact that there are no mining companies in the Republic of Croatia where people could learn facts of mining companies and ventilation systems, which is very important in case of dangerous situations.