Application of an additional electrode for improving the emission properties of the lossless cathode-neutralizer for EPSPS

2020 ◽  
Author(s):  
A.S. Benklyan ◽  
A.A. Lyapin ◽  
G.K. Klimenko
Keyword(s):  
Laboratory Tests ◽  
Activation Process ◽  
Emitter Surface ◽  
Propulsion Systems ◽  
Hall Effect Thrusters ◽  
Ion Thrusters ◽  
Thermionic Cathodes ◽  
Basic Concepts ◽  
Additional Stimulation ◽  
Stimulation Of

The article considers the advantages of application of an additional electrode — anode-collector in the design of a lossless cathode-neutralizer (LCN) for electrically powered spacecraft propulsion systems (EPSPS) (hall-effect thrusters and ion thrusters). The relevance of the work is due to the increased interest in the possibility of using lossless thermionic cathodes as cathodes-neutralizers (CN) of EPSPS. Based on the results of laboratory tests of the lossless cathode-neutralizer model conclusions are drawn about the effectiveness of the anode-collector in the design of the lossless cathode-neutralizer. The presence of the collector-anode allows for additional “stimulation” of the emitter by voltage intensifying the emitter activation process and increasing the emission current from the emitter surface by 2-2.3 times. The saved energy for emitter heating due to using an anode-collector is estimated. The basic concepts and recommendations for the development of the design of lossless cathode-neutralizer design are presented.

Stimulation of Common Cocklebur (Xanthium pensylvanicum) and Redroot Pigweed (Amaranthus retroflexus) Seed Germination by Injections of Ethylene into Soil

Weed Science ◽  
1980 ◽  
Vol 28 (5) ◽  
pp. 510-514 ◽  
Author(s):  
G. H. Egley
Keyword(s):  
Seed Germination ◽  
Laboratory Tests ◽  
Seedling Emergence ◽  
Amaranthus Retroflexus ◽  
Redroot Pigweed ◽  
Plastic Bags ◽  
Viable Seeds ◽  
Chamber Studies ◽  
Growth Chamber Studies ◽  
Stimulation Of

The effects of ethylene upon germination of common cocklebur (Xanthium pensylvanicumWallr.) and redroot pigweed (Amaranthus retroflexusL.) seeds were studied. In laboratory tests with seeds in sealed flasks in the dark, 10 μl/L ethylene increased germination of redroot pigweed seeds from 7% to 52% at 30 C, and increased germination of large and small common cocklebur seeds from 30% and 0% to 100% and 90% respectively, at 25 C. At least 12 h of exposure to ethylene was necessary for appreciable stimulation of germination. In growth chamber studies with known numbers of seeds in pots of soil, ethylene at 11 kg/ha was injected into the soil, and the pots were enclosed in plastic bags for 24 h. One such injection at 2 weeks after planting, and successive injections at 2, 3, and 4 weeks, significantly increased redroot pigweed seedling emergence, and significantly decreased the numbers of dormant, viable seeds remaining in the soil. When pots were not enclosed, injections did not significantly effect redroot pigweed seeds, but significantly increased common cocklebur seedling emergence and decreased the number of viable common cocklebur seeds remaining in the soil.

scholarly journals In vivo stimulation of I kappa B phosphorylation is not sufficient to activate NF-kappa B.

1995 ◽  
Vol 15 (3) ◽  
pp. 1294-1301 ◽  
Author(s):  
I Alkalay ◽  
A Yaron ◽  
A Hatzubai ◽  
S Jung ◽  
A Avraham ◽  
...  
Keyword(s):  
T Cell Activation ◽  
Cell Activation ◽  
Extended Period ◽  
Activation Process ◽  
Nf Kappa B ◽  
Inflammatory Reactions ◽  
I Kappa B Alpha ◽  
Cytoplasmic Complex ◽  
Stimulation Of

NF-kappa B is a major inducible transcription factor in many immune and inflammatory reactions. Its activation involves the dissociation of the inhibitory subunit I kappa B from cytoplasmic NF-kappa B/Rel complexes, following which the Rel proteins are translocated to the nucleus, where they bind to DNA and activate transcription. Phosphorylation of I kappa B in cell-free experiments results in its inactivation and release from the Rel complex, but in vivo NF-kappa B activation is associated with I kappa B degradation. In vivo phosphorylation of I kappa B alpha was demonstrated in several recent studies, but its role is unknown. Our study shows that the T-cell activation results in rapid phosphorylation of I kappa B alpha and that this event is a physiological one, dependent on appropriate lymphocyte costimulation. Inducible I kappa B alpha phosphorylation was abolished by several distinct NF-kappa B blocking reagents, suggesting that it plays an essential role in the activation process. However, the in vivo induction of I kappa B alpha phosphorylation did not cause the inhibitory subunit to dissociate from the Rel complex. We identified several protease inhibitors which allow phosphorylation of I kappa B alpha but prevent its degradation upon cell stimulation, presumably through inhibition of the cytoplasmic proteasome. In the presence of these inhibitors, phosphorylated I kappa B alpha remained bound to the Rel complex in the cytoplasm for an extended period of time, whereas NF-kappa B activation was abolished. It appears that activation of NF-kappa B requires degradation of I kappa B alpha while it is a part of the Rel cytoplasmic complex, with inducible phosphorylation of the inhibitory subunit influencing the rate of degradation.

scholarly journals Impact of Cryogenics on Cavitation through an Orifice: A Review

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8319
Author(s):  
Claudia Esposito ◽  
Johan Steelant ◽  
Maria Rosaria Vetrano
Keyword(s):  
State Of The Art ◽  
The State ◽  
Hydrodynamic Cavitation ◽  
Knowledge Gaps ◽  
Propulsion Systems ◽  
Clear Vision ◽  
Basic Concepts ◽  
The Impact

Cryogenic cavitation affects the operation of liquid propulsion systems during the first phase of a launch. Its effects within orifices or turbopumps can range from mild instabilities to catastrophic damages to the structures, jeopardizing the launch itself. Therefore, to ensure the proper designing of propulsion systems, cavitation phenomena cannot be neglected. Although hydrodynamic cavitation has been studied for decades, the impact of the nature of the fluid has been sparsely investigated. Therefore, this review, beginning from the basic concepts of cavitation, analyzes the literature dedicated to hydrodynamic cryogenic cavitation through an orifice. Our review provides a clear vision of the state-of-the-art from experimental and modeling viewpoints, identifies the knowledge gaps in the literature, and proposes a way to further investigate cryogenic cavitation in aerospace science.

Oscillator Basics

2016 ◽  
Author(s):  
Erwin B. Montgomery
Keyword(s):  
Nervous System ◽  
Fourier Transform ◽  
Oscillatory Activity ◽  
Neural Oscillators ◽  
Fundamental Understanding ◽  
Basic Concepts ◽  
The Fourier Transform ◽  
Frequency Phase ◽  
Stimulation Of

This chapter uses metaphors to help programmers picture the basic concepts of oscillators. At the least, DBS can be considered as oscillatory stimulation of the nervous system and increasingly, it is likely that the nervous system operates on the bases of neuronal and neural oscillators. Thus, a fundamental understanding of oscillators, particularly their features, is important. The defining feature of oscillatory activity is the recurrence or repetition of a phenomenon, such as the repetitive flashing of a light at a railroad crossing. This chapter uses the metaphor of a racecar circling on a racetrack that become increasing more complicated. The metaphors provide an appreciation of the features and properties of oscillators, such as amplitude, frequency, phase, period, and reasonance. The metaphors also provide an intuitive understanding of the methods used to decompose and analyze complex oscillators such as the Fourier Transform.

Neurobiology of the Gorgonian Coelenterates, Muricea Californica And Lophogorgia Chilensis: I. Behavioural Physiology

1979 ◽  
Vol 79 (1) ◽  
pp. 191-204
Author(s):  
RICHARD A. SATTERLIE ◽  
JAMES F. CASE
Keyword(s):  
Mechanical Stimulation ◽  
Liver Extract ◽  
Chemical Stimulation ◽  
Conduction System ◽  
Electrical Impulses ◽  
Additional Stimulation ◽  
Oral Disk ◽  
Stimulation Of ◽  
Conduction Properties ◽  
Stimulus Number

1. Electrical or mechanical stimulation of Muricea californica or Lophogorgia chilensis colonies resulted in withdrawal of polyps in the immediate vicinity of the stimulation point. Additional stimulation did not result in further spread of polyp retraction. 2. Electrical activity was recorded from a colonial conduction system not restricted to the area of polyp withdrawal. Conduction velocity in this conduction system decreased with increasing stimulus number and distance from the stimulation point. 3. Polyp withdrawal in Muricea occurred concomitantly with a burst of facilitating electrical impulses. The withdrawal burst was always preceded by impulses of the colonial conduction system. 4. The pattern of colonial behaviour in gorgonians depends upon the conduction properties of the colonial conduction system, the conduction system(s) of each individual polyp, and the pathways connecting the two. 5. Polyp tentacles bend to the oral disk when presented with liver extract. A burst of electrical impulses was recorded from Muricea polyps during chemical stimulation. These bursts exhibited apparent adaptation and presumably represent muscle potentials resulting from chemoreceptor activation.

Separation of factors responsible for change in breathing pattern induced by instrumentation

1985 ◽  
Vol 59 (5) ◽  
pp. 1515-1520 ◽  
Author(s):  
W. Perez ◽  
M. J. Tobin
Keyword(s):  
Tidal Volume ◽  
Breathing Pattern ◽  
Minute Ventilation ◽  
Sensory Receptors ◽  
Inspiratory Time ◽  
Expiratory Time ◽  
Oral Breathing ◽  
Oral Stimulation ◽  
Additional Stimulation ◽  
Stimulation Of

Employment of mouthpiece and noseclips (MP + NC) has repeatedly been shown to increase tidal volume (VT), but its effect on respiratory frequency (f) and its subsets is controversial. The mechanisms accounting for this alteration in breathing pattern are poorly understood and may include stimulation of oral or nasal sensory receptors or alteration in the route of breathing. In this study we demonstrated that use of a MP + NC, compared with nonobtrusive measurement with a calibrated respiratory inductive plethysmograph, alters the majority of the volume and time indexes of breathing pattern, with increases in minute ventilation (P less than 0.01), VT (P less than 0.001), inspiratory time (TI, P less than 0.05), expiratory time (TE, P less than 0.05), mean inspiratory flow (P less than 0.05), and mean expiratory flow (P less than 0.05) and a decrease in f(P less than 0.05). Separating the potential mechanisms we found that when the respiratory route was not altered, independent oral stimulation (using an occluded MP) or nasal stimulation (by applying paper clips to the alae nasi) did not change the breathing pattern. In contrast, obligatory oral breathing without additional stimulation of the oral or nasal sensory receptors caused increases in VT (P less than 0.05), TI (P less than 0.05), and TE (P less than 0.01) and a fall in f(P less than 0.05). Heating and humidifying the inspired air did not prevent the alteration in breathing pattern with a MP. Thus change in the respiratory route is the major determinant of the alteration in breathing pattern with a MP + NC.

scholarly journals Volume compression and volume ignition of laser driven fusion pellets

1989 ◽  
Vol 7 (3) ◽  
pp. 511-520 ◽  
Author(s):  
G. Kasotakis ◽  
L. Cicchitelli ◽  
H. Hora ◽  
R. J. Stening
Keyword(s):  
Close Agreement ◽  
Initial Temperature ◽  
Fusion Energy ◽  
The Self ◽  
Fusion Reactions ◽  
Nuclear Fusion Reactions ◽  
Volume Compression ◽  
Volume Ignition ◽  
Additional Stimulation ◽  
Stimulation Of

Volume compression and volume ignition of laser compressed pellets has an enormous advantage against spark ignition since the alpha self-heat substantially contributes as an additional stimulation of nuclear fusion reactions. We present here improved computations of volume ignition in agreement with the classical fact that the generated fusion energy is larger than the bremsstrahlung energy in DT only at temperatures above 4·5 keV. This result is in very close agreement with Kidder's (1974) values, and in agreement with recent computations of Mimaet al.(1987). The extension of these calculations to higher densities and input energies results in the self-absorption of bremsstrahlung at an initial temperature of about 1 keV only, much below the classical 4·5 keV. A fuel burnup fraction above 80% is shown to be possible.

scholarly journals INFLUENCE OF WALL SCATTERING EFFECT ON ELECTRONS GAS DYNAMICS PARAMETERS IN ELECTRIC PROPULSION THRUSTERS WITH CLOSED ELECTRON DRIFT

2021 ◽  
Author(s):  
Guo Zongshuai, ◽  
Huang Zhihao
Keyword(s):  
Mathematical Modeling ◽  
Gas Dynamics ◽  
Electric Propulsion ◽  
Electron Drift ◽  
Dense Gases ◽  
Equations Of Gas Dynamics ◽  
Hall Effect Thrusters ◽  
Ion Thrusters ◽  
The Common ◽  
Closed Electron

The analysis is represented of some works devoted to the mathematical modeling of processes in plasma-ion thrusters and Hall effect thrusters. It is shown that the common in these works is the use of approximate forms of the equations of gas dynamics, which are applicable to the description of relatively dense gases, but not to analyze the processes in the rarefied plasma of electric propulsion thrusters. As a result, the above mathematical models do not represent the processes that are significantly responsible for the values of the thruster operating parameters.Authors try to partially correct this drawback by insertion into the initial approximate forms of the equations written for a point in the plasma volume, the parameters that actually represent the boundary effects and should be written not in the equations of gas dynamics themselves, but in the boundary conditions for these equations.The most complete forms of the necessary equations are given in this paper. It is shown that it is necessary to take into account electrons thermal conductivity as well as at least one (radial-azimuth) component of viscosity tensor to describe the "wall scattering" effect.It is concluded that the most productive approach in mathematical modeling is to write the most complete forms of equations with their subsequent simplification – removing the terms responsible for the processes recognized on the basis of primary numerical estimates as such, which can be neglected.

scholarly journals A Kinase Activity Associated with Simian Virus 40 Large T Antigen Phosphorylates Upstream Binding Factor (UBF) and Promotes Formation of a Stable Initiation Complex between UBF and SL1

1999 ◽  
Vol 19 (4) ◽  
pp. 2791-2802 ◽  
Author(s):  
Weiguo Zhai ◽  
Lucio Comai
Keyword(s):  
Kinase Activity ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Activation Process ◽  
Large T Antigen ◽  
Pol I ◽  
Binding Factor ◽  
Upstream Binding Factor ◽  
Stimulation Of

ABSTRACT Simian virus 40 large T antigen is a multifunctional protein which has been shown to modulate the expression of genes transcribed by RNA polymerase I (Pol I), II, and III. In all three transcription systems, a key step in the activation process is the recruitment of large T antigen to the promoter by direct protein-protein interaction with the TATA binding protein (TBP)-TAF complexes, namely, SL1, TFIID, and TFIIIB. However, our previous studies on large T antigen stimulation of Pol I transcription also revealed that the binding to the TBP-TAFI complex SL1 is not sufficient to activate transcription. To further define the molecular mechanism involved in large T antigen-mediated Pol I activation, we examined whether the high-mobility group box-containing upstream binding factor (UBF) plays any role in this process. Here, using cell labeling experiments, we showed that large T antigen expression induces an increase in UBF phosphorylation. Further biochemical analysis demonstrated that UBF is phosphorylated by a kinase activity that is strongly associated with large T antigen, and that the carboxy-terminal activation domain of UBF is required for the phosphorylation to occur. Using in vitro reconstituted transcription assays, we demonstrated that the inability of alkaline phosphatase treated UBF to efficiently activate transcription can be rescued by large T antigen. Moreover, we showed that large T antigen-induced UBF phosphorylation promotes the formation of a stable UBF-SL1 complex. Together, these results provide strong evidence for an important role for the large T antigen-associated kinase in mediating the stimulation of RNA Pol I transcription.

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