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Shape Selective Oxygen Transfer to Olefins Catalyzed by Sterically Hindered Iron Porphyrins
Ahn, Kwang-Hyun,Groves, John T. Korean Chemical Society 1994 Bulletin of the Korean Chemical Society Vol.15 No.11
Epoxidation of olefins catalyzed by iron-tetraarylporphyrins were studied to see the shape selectivity in the competing reaction between cis-and trans- or internal and external olefins. Cis-olefins were more reactive than trans-olefins in the competing reaction between cis-and trans-olefins. Interestingly, in the epoxidation of $cis-{\beta}-methystyrene$ by ${\alpha}{\beta}{\alpha}{\beta}$ atropisomer of Fe(III)TNPPPCl and iodosylbenzene, 27% of total product was phenylacetone. The unusually large amount of phenylacetone may be produced by hydride rearrangement of carbocationic intermediate. Regioselectivity of the reaction was also studied by using the most sterically hindered Fe(III)TTPPPCl. In the epoxidation of limonene with Fe(III)TTPPPCl, the disubstituted double bond was more reactive than trisubstituted double bond. This is in contrast to the results obtained with other iron-tetraarylporphyrins. Similar trend was also observed in the competing reaction between mono-and di-substituted olefins.
Chip formation of rounded cutting edges
B. Bergmann,B. Denkena,T. Grove,T. Picker 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.1
In cutting processes, the performance and tool life of cutting tools are important evaluation criterions. The cutting edge microgeometry of the tools is in direct contact with the workpiece and thus influences the material flow and the loads on the cutting wedge. Research to date has demonstrated the potential of rounded cutting edges and their improved wear behavior. However, the investigations were always limited to a certain number of materials or processes. For a process-specific design of the cutting edge microgeometry, it must be possible to explicitly describe the material- and process-related contact conditions during machining with rounded cutting edges. Hence, the following article analyzes the chip formation of different cutting edge microgeometries during machining in continuous and interrupted cutting. For this purpose, planing tests on non-ferrous and ferrous materials as well as milling tests on steel alloys with differently rounded cutting tools are carried out and the effects on the chip formation process are analyzed. The results show that the minimum uncut chip thickness hmin correlates linearly to the cutting edge rounding. In addition, the correlation obtained is independent of the cutting process and the workpiece material.
The SAMI Galaxy Survey: observing the environmental quenching of star formation in GAMA groups
Schaefer, A L,Croom, S M,Scott, N,Brough, S,Allen, J T,Bekki, K,Bland-Hawthorn, J,Bloom, J V,Bryant, J J,Cortese, L,Davies, L J M,Federrath, C,Fogarty, L M R,Green, A W,Groves, B,Hopkins, A M,Konstant Oxford University Press 2019 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.483 No.3