Energy degradation of fast electrons in hydrogen gas

1991 ◽  
Vol 375 ◽  
pp. 190 ◽  
Author(s):  
Yueming Xu ◽  
Richard McCray
Keyword(s):  
Hydrogen Gas ◽  
Fast Electrons ◽  
Energy Degradation

Motions of neutral hydrogen at high latitudes

1967 ◽  
Vol 31 ◽  
pp. 265-278 ◽  
Author(s):  
A. Blaauw ◽  
I. Fejes ◽  
C. R. Tolbert ◽  
A. N. M. Hulsbosch ◽  
E. Raimond
Keyword(s):  
Surface Density ◽  
Velocity Dispersion ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
High Latitudes ◽  
Low Velocity

Earlier investigations have shown that there is a preponderance of negative velocities in the hydrogen gas at high latitudes, and that in certain areas very little low-velocity gas occurs. In the region 100° <l< 250°, + 40° <b< + 85°, there appears to be a disturbance, with velocities between - 30 and - 80 km/sec. This ‘streaming’ involves about 3000 (r/100)2solar masses (rin pc). In the same region there is a low surface density at low velocities (|V| < 30 km/sec). About 40% of the gas in the disturbance is in the form of separate concentrations superimposed on a relatively smooth background. The number of these concentrations as a function of velocity remains constant from - 30 to - 60 km/sec but drops rapidly at higher negative velocities. The velocity dispersion in the concentrations varies little about 6·2 km/sec. Concentrations at positive velocities are much less abundant.

Design of Sensitive Photographic Materials for the High-Voltage Electron Microscope

1975 ◽  
Vol 33 ◽  
pp. 156-157
Author(s):  
Murray Vernon King ◽  
Donald F. Parsons
Keyword(s):  
Electron Microscope ◽  
Radiation Damage ◽  
High Voltage ◽  
Radiation Sensitivity ◽  
Fast Electrons ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Biological Studies ◽  
Low Sensitivity

Effective application of the high-voltage electron microscope to a wide variety of biological studies has been restricted by the radiation sensitivity of biological systems. The problem of radiation damage has been recognized as a serious factor influencing the amount of information attainable from biological specimens in electron microscopy at conventional voltages around 100 kV. The problem proves to be even more severe at higher voltages around 1 MV. In this range, the problem is the relatively low sensitivity of the existing recording media, which entails inordinately long exposures that give rise to severe radiation damage. This low sensitivity arises from the small linear energy transfer for fast electrons. Few developable grains are created in the emulsion per electron, while most of the energy of the electrons is wasted in the film base.

High-angle electron scattering from amorphous silicon

1995 ◽  
Vol 53 ◽  
pp. 162-163
Author(s):  
M. Libera ◽  
J.A. Ott ◽  
K. Siangchaew ◽  
L. Tsung
Keyword(s):  
Electron Scattering ◽  
Amorphous Material ◽  
Structural Defects ◽  
Constant Thickness ◽  
High Angle ◽  
Fast Electrons ◽  
Angle Scattering ◽  
Stem Image ◽  
Amorphous Si ◽  
Thermal Vibrations

Channeling occurs when fast electrons follow atomic strings in a crystal where there is a minimum in the potential energy (1). Channeling has a strong effect on high-angle scattering. Deviations in atomic position along a channel due to structural defects or thermal vibrations increase the probability of scattering (2-5). Since there are no extended channels in an amorphous material the question arises: for a given material with constant thickness, will the high-angle scattering be higher from a crystal or a glass?Figure la shows a HAADF STEM image collected using a Philips CM20 FEG TEM/STEM with inner and outer collection angles of 35mrad and lOOmrad. The specimen (6) was a cross section of singlecrystal Si containing: amorphous Si (region A), defective Si containing many stacking faults (B), two coherent Ge layers (CI; C2), and a contamination layer (D). CBED patterns (fig. lb), PEELS spectra, and HAADF signals (fig. lc) were collected at 106K and 300K along the indicated line.

PERLAKUAN ETHYL METHANE SULFONATE (EMS) PADA ENTEROBACTER AEROGENES AY-2 DARI LIMBAH METAN FERMENTASI UNTUK PENINGKATAN PRODUKSI GAS HIDROGEN

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Mahyudin Abdul Rachman
Keyword(s):  
Metabolic Pathway ◽  
Acid Production ◽  
Double Mutant ◽  
Enterobacter Aerogenes ◽  
H2 Production ◽  
Hydrogen Gas ◽  
Survival Ratio ◽  
Ethyl Methane Sulfonate ◽  
Methane Sulfonate ◽  
Ethyl Methane

Enterobacter aerogenes AY-2 mutant is known for hydrogen gas producer which ws obtained from the sludge of methane fermentation and the yield is 1.5 fold higher than wildtype. Hydrogen gas production can be gain via NADH oxidation in anaerobic metabolic pathway by blocking organic acid production. Metabolic pathway can be changed by mutagenesis. Enterobacter aerogenes AY-2 mutated with ethyl methane sulfonate in logarithmic phase with consentration 10, 11, 12, 13, 14 and 15 μl/ml cell suspention during 120 minute. Mutation that result lowest survival ratio (0,01%) was 14 μl EMS/ml cell suspention is repeated with variation incubation time, 30, 60, 90 and 120 minute. 166 double mutant colony has been collected and choosen randomly. The choosen 43 colony was fermented in glycerol complex medium for determining ten double mutant with the highest H2 production. Double mutant AD-H43 is a highest H2 producer that increase 20% H2 production from AY-2 and has a decrease lactid acid production, 31% less from AY-2. Increasing H2 production in double mutant AD-H43 is caused by lactate dehydrogenase deffi cient.Keywords: Enterobacter aerogenes AY-2, ethyl methane sulfonate (EMS), H2 and methane sludge

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