Critical Störmer Conditions in Quadrupole and Double Ring‐Current Fields

1965 ◽  
Vol 6 (12) ◽  
pp. 1966-1975 ◽  
Author(s):  
Eugene W. Urban
Keyword(s):  
Ring Current ◽  
Double Ring

Ring current model of the naphthalene molecule

1997 ◽  
Vol 92 (3) ◽  
pp. 609-617 ◽  
Author(s):  
RICCARDO ZANASI ◽  
PAOLO LAZZERETTI
Keyword(s):  
Ring Current ◽  
Current Model ◽  
Naphthalene Molecule

Double Ring-Closing Approach for the Synthesis of 2,3,6,7-Substituted Anthracene Derivatives

2020 ◽  
Author(s):  
Birgit Meindl ◽  
Katharina Pfennigbauer ◽  
Berthold Stöger ◽  
Martin Heeney ◽  
Florian Glöcklhofer
Keyword(s):  
Wittig Reaction ◽  
Condensation Reaction ◽  
Synthetic Methods ◽  
Anthracene Derivative ◽  
Double Ring ◽  
Mild Conditions ◽  
Wide Range ◽  
Anthracene Derivatives

Anthracene derivatives have been used for a wide range of applications and many different synthetic methods for their preparation have been developed. However, despite continued synthetic efforts, introducing substituents in some positions has remained difficult. Here we present a method for the synthesis of 2,3,6,7-substituted anthracene derivatives, one of the most challenging anthracene substitution patterns to obtain. The method is exemplified by the preparation of 2,3,6,7-anthracenetetracarbonitrile and employs a newly developed, stable protected 1,2,4,5-benzenetetracarbaldehyde as the precursor. The precursor can be obtained in two scalable synthetic steps from 2,5-dibromoterephthalaldehyde and is converted into the anthracene derivative by a double intermolecular Wittig reaction under very mild conditions followed by a deprotection and intramolecular double ring-closing condensation reaction. Further modification of the precursor is expected to enable the introduction of additional substituents in other positions and may even enable the synthesis of fully substituted anthracene derivatives by the presented approach.<br>

Investigation of Ring Current/Storm Dynamics

1991 ◽  
Author(s):  
H. L. Collin ◽  
J. B. Cladis ◽  
J. M. Quinn
Keyword(s):  
Ring Current ◽  
Storm Dynamics

Survey of Ring Current Composition During Magnetic Storms

1998 ◽  
Author(s):  
M. Grande ◽  
C. H. Perry ◽  
A. Hall ◽  
J. Fennell ◽  
B. Wilken
Keyword(s):  
Ring Current ◽  
Magnetic Storms

scholarly journals University of Kiel Radiocarbon Measurements II

Radiocarbon ◽  
1967 ◽  
Vol 9 ◽  
pp. 257-260
Author(s):  
H. Willkomm ◽  
H. Erlenkeuser
Keyword(s):  
Proportional Counter ◽  
Atmospheric Pressure ◽  
Statistical Error ◽  
Quartz Tube ◽  
Sensitive Volume ◽  
Concrete Wall ◽  
Lead Shield ◽  
Double Ring

Most of the measurements reported here have been obtained with the 4.5-L CO2 counter previously described (Kiel I; Erlenkeuser, 1965). A few samples have been dated with a 3-L proportional counter. The copper counter is surrounded by 28 GM counters in the form of a double ring. The total assembly is shielded by 10 cm of old lead. Neither an inner lead shield between counter and anticoincidence ring nor screening of sensitive volume by a quartz tube-as in the 4.5-L counter-has been used. Background of the small counter is 17.20 cpm or The 0.95 x NBS value is 9.5 cpm at 400 torr. Within statistical error background does not depend on atmospheric pressure. The 3-L counter is placed under a concrete wall, 2.5 m in length and 9.4 m in height.

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