Suchergebnisse

The demand for both passenger and freight rail transport in Sweden has never before been higher than in the year 2008. There is now serious lack of capacity and big delays, and need for massive investment in rail. High-speed trains may be a way to relieve track congestion, reduce travel times and improve the environment through less air and car travel. The Swedish National Rail Administration has initiated a number of studies on the value of high-speed trains over the last years. The Swedish government has initiated a study that was finished 14 thof September 2009 and suggested to build a separate high speed tracks in Sweden. The paper describes the main findings of the study and the models employed. The latter is of importance since two models gave significantly different results, even though both showed a positive socio-economic net return. The cost-benefit calculations have also been subject to scepticism. These scepticisms are also described and commented. ; QC 20120229

[EN] It was found that either polymorph B or polymorph C of zeolite beta can be obtained from the same structure directing agent: 4,4-dimethyl-4-azonia-tricyclo[5.2.2.0(2,6)] undec-8-ene hydroxide. The synthesis occurs through a consecutive process where polymorph B is first formed and then transformed into polymorph C. It is possible to produce a zeolite highly enriched in polymorph B, provided that the transformation of this phase into polymorph C is slowed down up to the point where polymorph C is only detected at trace levels. The structure of polymorph B was determined for the first time by electron crystallography with SAED and HRTEM from areas of unfaulted polymorph B crystals. ; Financial support from the Spanish Government (Project MAT2006-14274-C02–01) and the EU Commission (TOPCOMBI Project) is gratefully acknowledged. M.M. thanks CSIC for an I3P grant. J.S. is supported by a postdoctoral grant from the Carl Trygger Foundation. The Berzelii Centre EXSELENT is supported by the Swedish Research Council (VR) and the Swedish Governmental Agency for Innovation Systems (VINNOVA). ; Corma Canós, A.; Moliner Marin, M.; Cantin Sanz, A.; Díaz Cabañas, MJ.; Jorda Moret, JL.; Zhang, D.; Sun, J. (2008). Synthesis and structure of polymorph B of zeolite Beta. Chemistry of Materials. 20(9):3218-3223. doi:10.1021/cm8002244 ; S ; 3218 ; 3223 ; 20 ; 9