An inexpensive apparatus for up to 97% continuous-flow parahydrogen enrichment using liquid helium

2020 ◽  
Vol 321 ◽  
pp. 106869
Author(s):  
Yong Du ◽  
Ronghui Zhou ◽  
Maria-Jose Ferrer ◽  
Minda Chen ◽  
John Graham ◽  
...  
Cryogenics ◽  
1977 ◽  
Vol 17 (1) ◽  
pp. 33-42 ◽  
Author(s):  
W.B. Bald ◽  
H. Zust ◽  
W.G. Wooster

2019 ◽  
Vol 203 ◽  
pp. 12-20
Author(s):  
Felix Börrnert ◽  
Felix Kern ◽  
Franziska Harder ◽  
Thomas Riedel ◽  
Heiko Müller ◽  
...  

Author(s):  
R. E. Worsham ◽  
J. E. Mann ◽  
E. G. Richardson

This superconducting microscope, Figure 1, was first operated in May, 1970. The column, which started life as a Siemens Elmiskop I, was modified by removing the objective and intermediate lenses, the specimen chamber, and the complete vacuum system. The large cryostat contains the objective lens and stage. They are attached to the bottom of the 7-liter helium vessel and are surrounded by two vapor-cooled radiation shields.In the initial operational period 5-mm and 2-mm focal length objective lens pole pieces were used giving magnification up to 45000X. Without a stigmator and precision ground pole pieces, a resolution of about 50-100Å was achieved. The boil-off rate of the liquid helium was reduced to 0.2-0.3ℓ/hour after elimination of thermal oscillations in the cryostat. The calculated boil-off was 0.2ℓ/hour. No effect caused by mechanical or electrical instability was found. Both 4.2°K and 1.7-1.9°K operation were routine. Flux pump excitation and control of the lens were quite smooth, simple, and, apparently highly stable. Alignment of the objective lens proved quite awkward, however, with the long-thin epoxy glass posts used for supporting the lens.


Author(s):  
M.K. Lamvik ◽  
D.A. Kopf ◽  
S.D. Davilla ◽  
J.D. Robertson

Last year we reported1 that there is a striking reduction in the rate of mass loss when a specimen is observed at liquid helium temperature. It is important to determine whether liquid helium temperature is significantly better than liquid nitrogen temperature. This requires a good understanding of mass loss effects in cold stages around 100K.


2020 ◽  
Vol 22 (19) ◽  
pp. 6437-6443
Author(s):  
Cheng-Kou Liu ◽  
Meng-Yi Chen ◽  
Xin-Xin Lin ◽  
Zheng Fang ◽  
Kai Guo

A catalyst-, oxidant-, acidic solvent- and quaternary ammonium salt-free electrochemical para-selective hydroxylation of N-arylamides at rt in batch and continuous-flow was developed.


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