Methodology for developing a low-pressure discharge lamp model with electron density variation and ambipolar diffusion

2012 ◽  
Vol 6 (4) ◽  
pp. 229 ◽  
Author(s):  
D. Lin ◽  
W. Yan ◽  
G. Zissis ◽  
S.Y.R. Hui
Keyword(s):  
Electron Density ◽  
Low Pressure ◽  
Density Variation ◽  
Ambipolar Diffusion ◽  
Discharge Lamp ◽  
Pressure Discharge ◽  
Electron Density Variation

A Biological System Producing a Self-Assembling Cholesteric Protein Liquid Crystal

1971 ◽  
Vol 8 (1) ◽  
pp. 93-109
Author(s):  
A. C. NEVILLE ◽  
B. M. LUKE
Keyword(s):  
Liquid Crystal ◽  
Electron Density ◽  
Electron Micrographs ◽  
Self Assembly ◽  
Liquid Crystalline ◽  
Density Variation ◽  
Self Assembling ◽  
The Matrix ◽  
Electron Density Variation ◽  
Helicoidal Structure

The protein in the oothecal glands of praying mantids (Sphodromantis tenuidentata, Miomantis monacha) exists in the form of lamellar liquid crystalline spherulites, which coalesce as they flow out of a punctured gland tubule. Electron micrographs of sections of these spherulites after fixation show parabolic patterns of an electron-light component, set in a continuous matrix of protein. Such patterns arise in helicoidal systems (e.g. arthropod cuticle) and microdensitometric scans of the matrix show a rhythmical electron-density variation consistent with helicoidal structure. Double spiral patterns identical to those seen in liquid crystal spherulites are illustrated. These properties resemble those of cholesteric liquid crystals. The constructional units appear to be molecular rather than fibrillar as described by previous authors. The helicoidal architecture arises by self-assembly in the gland lumen. Lamellar surface structures self-assembled spontaneously on glass coverslips when the protein was left to stand for several days. When heated to 55 °C, the birefringent liquid crystalline protein abruptly changes to an isotropic gel, with associated loss of parabolic patterning in electron micrographs and of the rhythmical electron-density variation on microdensitometric scans. This behaviour is compared to the formation of gelatin from collagen, in terms of the randomization of an originally ordered secondary structure.

scholarly journals Investigation of the Electron Density Variation During the 21 August 2017 Solar Eclipse

2018 ◽  
Vol 45 (3) ◽  
pp. 1253-1261 ◽  
Author(s):  
B. W. Reinisch ◽  
P. B. Dandenault ◽  
I. A. Galkin ◽  
R. Hamel ◽  
P. G. Richards
Keyword(s):  
Electron Density ◽  
Solar Eclipse ◽  
Density Variation ◽  
Electron Density Variation

scholarly journals Enhanced Radio Source Scintillation due to Comet Austin (1989c1)

1991 ◽  
Vol 44 (5) ◽  
pp. 565 ◽  
Author(s):  
P Janardhan ◽  
SK Alurkar ◽  
AD Bobra ◽  
OB Slee
Keyword(s):  
Solar Wind ◽  
Radio Source ◽  
Electron Density ◽  
Density Variation ◽  
Scintillation Index ◽  
The Sun ◽  
Interplanetary Scintillation ◽  
Electron Density Variation ◽  
Comet Halley

Enhanced scintillations in the direction of the quasar 2204+29 (3C441) were observed on 13 May 1990 when the tail of Comet Austin passed in front of it. Comparison with previous observations at 103, 327 and 408 MHz of Comet Halley and at 408 MHz of Comet Wilson show that proper occultation geometry is essential for observing enhanced scintillations. It has been shown that the solar elongation ? during such observations should be large, typically greater than 60� and in no case less than 30� at 103 MHz. At the time of the occultation the scintillation index (r.m.s./mean source flux) was greater than that expected for this source by a factor of 3. The r.m.s. electron density variation /IN, at a distance of 0�9 A.U. from the sun and 7�3� downstream of the nucleus, was found to be 6 cm-3 as compared with 1 cm-3 for the normal solar wind at 1 A.U. The corresponding scale sizes of the turbulence were found to be much finer than normally found in interplanetary scintillation (IPS) caused by the solar wind.

Sign in / Sign up

Export Citation Format

Share Document