A time-correlated study of the Z-pinch discharge in helium

The development of a miniature "gradient probe" and the successful superposition of multiple photographic recordings have produced useful insight into the action of the Z-pinch discharge in helium.A correlation of luminosity and current fronts yields strong evidence for the occurrence of a nonionizing shock wave at high initial pressures in helium discharges. The relatively nonluminous shock front is followed by overlapping regions of He I and He II radiation within the collapsing current shell. At low filling pressures these two regions coincide and radiation is emitted from almost all the gas trapped within the current shell. In all cases the zone of maximum He II emission is observed to coincide with the position of maximum current density.Synchronization of the discharge current with time-resolved spectroscopic results indicates the presence of successive pinches. They are caused by the interaction of thermal and magnetic pressures after the first collapse of the discharge.

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Soft X-ray lasing at 519.7 Å in a Recombining Z-pinch Plasma

Laser and Particle Beams ◽

10.1017/s0263034600011162 ◽

1997 ◽

Vol 15 (4) ◽

pp. 589-595 ◽

Cited By ~ 6

Author(s):

E. Eberl ◽

T. Wagner ◽

J. Jacoby ◽

A. Tauschwitz ◽

D.H.H. Hoffmann

Keyword(s):

Discharge Current ◽

Line Intensity ◽

Gas Pressure ◽

Time Resolved ◽

X Ray ◽

Pinch Plasma ◽

Gain Length ◽

Z Pinch ◽

Time Resolved Measurements

This paper is reviewing the amplification of XUV radiation at 519.7 and 498.5 Å with a gain-length product of 2.5 and 2.2 for the 4f-3d and 4d-3p transition in an oxygen Z-pinch plasma. Time resolved measurements of the O VI (519.7 Å) transition were performed and the dependence of the line intensity on the discharge current and initial gas pressure is reported.

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Experimentelle Untersuchungen zur Dynamik elektromagnetisch angetriebener konvergenter Zylinderstoßwellen

Zeitschrift für Naturforschung A ◽

10.1515/zna-1968-0409 ◽

1968 ◽

Vol 23 (4) ◽

pp. 514-520

Author(s):

U. Kogelschatz ◽

W. Bötticher ◽

H. Dammann ◽

G. Kleist

Keyword(s):

Shock Wave ◽

Shock Front ◽

Filling Pressure ◽

Total Current ◽

Considerable Part ◽

Cylindrical Shock Wave ◽

Moving Plasma ◽

Current Flows ◽

Z Pinch ◽

Probe Measurements

In the convergent cylindrical shock wave of a Z-pinch discharge (diameter/length ratio : 44 cm per 10 cm), magnetic probe measurements have been made of the current density and the velocity of the current sheet. For discharges in Helium, Argon and Krypton at mass densities from 2.2·10-7 to 5.5·10-6 g/cm3 one finds: 1. Only a small portion of the total current contracts with the shock wave. The direction of this current is maintained even when the total current reverses. 2. The gas pressure behind the shock front is a constant for each gas independent of the filling pressure. 3. At small radii the contraction is determined by the inertia of the moving plasma only. 4. With higher filling pressures a considerable part of the small contracting current flows ahead of the shock front.

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Investigation of shock-wave deformation history from recovered structure

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143754 ◽

1986 ◽

Vol 44 ◽

pp. 434-435

Author(s):

M.A. Mogilevsky ◽

L.S. Bushnev

Keyword(s):

Shock Wave ◽

Plastic Deformation ◽

Dislocation Density ◽

Shock Waves ◽

Shock Front ◽

Single Crystals ◽

Residual Deformation ◽

Deformation Structure ◽

Deformation History ◽

Deformation Velocity

Single crystals of Al were loaded by 15 to 40 GPa shock waves at 77 K with a pulse duration of 1.0 to 0.5 μs and a residual deformation of ∼1%. The analysis of deformation structure peculiarities allows the deformation history to be re-established.After a 20 to 40 GPa loading the dislocation density in the recovered samples was about 1010 cm-2. By measuring the thickness of the 40 GPa shock front in Al, a plastic deformation velocity of 1.07 x 108 s-1 is obtained, from where the moving dislocation density at the front is 7 x 1010 cm-2. A very small part of dislocations moves during the whole time of compression, i.e. a total dislocation density at the front must be in excess of this value by one or two orders. Consequently, due to extremely high stresses, at the front there exists a very unstable structure which is rearranged later with a noticeable decrease in dislocation density.

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Intermittent maser flare around the high-mass young stellar object G353.273+0.641

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312006722 ◽

2012 ◽

Vol 8 (S287) ◽

pp. 98-102

Author(s):

Kazuhito Motogi ◽

Kazuo Sorai ◽

Kenta Fujisawa ◽

Koichiro Sugiyama ◽

Mareki Honma

Keyword(s):

Light Curve ◽

Small Area ◽

Linear Acceleration ◽

High Mass ◽

Velocity Range ◽

Time Resolved ◽

Almost All ◽

Maser Sources ◽

Water Maser

AbstractThe water maser site associated with G353.273+0.641 is classified as a dominant blueshifted H2O maser, which shows an extremely wide velocity range (± 100 km s−1) with almost all flux concentrated in the highly blueshifted emission. The previous study has proposed that this peculiar H2O maser site is excited by a pole-on jet from high mass protostellar object. We report on the monitoring of 22-GHz H2O maser emission from G353.273+0.641 with the VLBI Exploration of Radio Astrometry (VERA) and the Tomakamai 11-m radio telescope. Our VLBI imaging has shown that all maser features are distributed within a very small area of 200 × 200 au2, in spite of the wide velocity range (> 100 km s−1). The light curve obtained by weekly single-dish monitoring shows notably intermittent variation. We have detected three maser flares during three years. Frequent VLBI monitoring has revealed that these flare activities have been accompanied by a significant change of the maser alignments. We have also detected synchronized linear acceleration (−5 km s−1yr−1) of two isolated velocity components, suggesting a lower-limit momentum rate of 10−3 M⊙ km s−1yr−1 for the maser acceleration. All our results support the previously proposed pole-on jet scenario, and finally, a radio jet itself has been detected in our follow-up ATCA observation. If highly intermittent maser flares directly reflect episodic jet-launchings, G353.273+0.641 and similar dominant blueshifted water maser sources can be suitable targets for a time-resolved study of high mass protostellar jet.

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Early Dynamics of a Laser-induced Underwater Shock Wave

Journal of Fluids Engineering ◽

10.1115/1.4051385 ◽

2021 ◽

Author(s):

Guihua Lai ◽

Siyuan Geng ◽

Hanwen Zheng ◽

Zhifeng Yao ◽

Qiang Zhong ◽

...

Keyword(s):

Shock Wave ◽

Numerical Method ◽

Cavitation Bubble ◽

Laser Energy ◽

Optical Breakdown ◽

Pulsed Laser ◽

Underwater Shock Wave ◽

Time Resolved ◽

High Attenuation ◽

Nanosecond Pulsed Laser

Abstract The objective of this paper is to observe and investigate the early evolution of the shock wave, induced by a nanosecond pulsed laser in still water. A numerical method is performed to calculate the propagation of the shock wave within 1µs, after optical breakdown, based on the Gilmore model and the Kirkwood-Bethe hypothesis. The input parameters of the numerical method include the laser pulse duration, the size of the plasma and the maximally extended cavitation bubble, which are measured utilizing a high time-resolved shadowgraph system. The calculation results are verified by shock wave observation experiments at the cavitation bubble expansion stage. The relative errors of the radiuses and the velocity of the shock wave front, reach the maximum value of 45% at 5 ns after breakdown and decrease to less than 20% within 20 ns. The high attenuation characteristics of the shock wave after the optical breakdown, are predicted by the numerical method. The quick time and space evolution of the shock wave are carefully analyzed. The normalized shock wave width is found to be independent of the laser energy and duration, and the energy partitions ratio is around 2.0 using the nanosecond pulsed laser.

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Numerical Simulation of Air Flow in the State of Thermal and Chemical Nonequilibrium behind a Shock Wave Front

Herald of the Bauman Moscow State Technical University Series Natural Sciences ◽

10.18698/1812-3368-2021-3-94-111 ◽

2021 ◽

pp. 94-111

Author(s):

A.I. Bryzgalov

Keyword(s):

Shock Wave ◽

Shock Front ◽

Wave Front ◽

Shock Wave Front ◽

Reaction Rate ◽

Vibrational Temperature ◽

Pure Oxygen ◽

Published Data ◽

Calculation Results ◽

Temperature Nonequilibrium

We used the model of a five-component air mixture flow behind the front of a one-dimensional shock wave to compute the flow parameters for shock front temperatures of up to 7000 K, taking into account the variable composition, translational and vibrational temperatures and pressure in the relaxation zone. Vibrational level population in oxygen and nitrogen obeys the Boltzmann distribution with one common vibrational temperature. We consider the effect that temperature nonequilibrium has on the chemical reaction rate by introducing a nonequilibrium factor to the reaction rate constant, said factor depending on the vibrational and translational temperatures. We compared our calculation results for dissociation behind the shock front to the published data concerning temperature nonequilibrium in a pure oxygen flow behind a shock wave front for two different intensities of the latter. The comparison shows a good agreement between the vibrational temperature, experimental data and calculations based on the experimental values of vibrational temperature and molality. We computed the parameters of thermodynamically nonequilibrium dissociation in the air behind the shock wave front, comparing them to those of equilibrium dissociation and calculation results previously published by others. The study demonstrates that the molality values computed converge gradually with those found in published data as the distance from the shock front increases. We list the reasons for the discrepancy between our calculation results and previously published data

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Comprehensive Comparative Genomics and Phenotyping of Methylobacterium Species

Frontiers in Microbiology ◽

10.3389/fmicb.2021.740610 ◽

2021 ◽

Vol 12 ◽

Author(s):

Ola Alessa ◽

Yoshitoshi Ogura ◽

Yoshiko Fujitani ◽

Hideto Takami ◽

Tetsuya Hayashi ◽

...

Keyword(s):

Comparative Genomics ◽

Phylogenetic Relationship ◽

Distinct Species ◽

Genotypic Differences ◽

Clade C ◽

Single Genus ◽

Almost All ◽

Type Strains ◽

Dependent Pathway ◽

Insight Into

The pink-pigmented facultative methylotrophs (PPFMs), a major bacterial group found in the plant phyllosphere, comprise two genera: Methylobacterium and Methylorubrum. They have been separated into three major clades: A, B (Methylorubrum), and C. Within these genera, however, some species lack either pigmentation or methylotrophy, which raises the question of what actually defines the PPFMs. The present study employed a comprehensive comparative genomics approach to reveal the phylogenetic relationship among the PPFMs and to explain the genotypic differences that confer their different phenotypes. We newly sequenced the genomes of 29 relevant-type strains to complete a dataset for almost all validly published species in the genera. Through comparative analysis, we revealed that methylotrophy, nitrate utilization, and anoxygenic photosynthesis are hallmarks differentiating the PPFMs from the other Methylobacteriaceae. The Methylobacterium species in clade A, including the type species Methylobacterium organophilum, were phylogenetically classified into six subclades, each possessing relatively high genomic homology and shared phenotypic characteristics. One of these subclades is phylogenetically close to Methylorubrum species; this finding led us to reunite the two genera into a single genus Methylobacterium. Clade C, meanwhile, is composed of phylogenetically distinct species that share relatively higher percent G+C content and larger genome sizes, including larger numbers of secondary metabolite clusters. Most species of clade C and some of clade A have the glutathione-dependent pathway for formaldehyde oxidation in addition to the H4MPT pathway. Some species cannot utilize methanol due to their lack of MxaF-type methanol dehydrogenase (MDH), but most harbor an XoxF-type MDH that enables growth on methanol in the presence of lanthanum. The genomes of PPFMs encode between two and seven (average 3.7) genes for pyrroloquinoline quinone-dependent alcohol dehydrogenases, and their phylogeny is distinctly correlated with their genomic phylogeny. All PPFMs were capable of synthesizing auxin and did not induce any immune response in rice cells. Other phenotypes including sugar utilization, antibiotic resistance, and antifungal activity correlated with their phylogenetic relationship. This study provides the first inclusive genotypic insight into the phylogeny and phenotypes of PPFMs.

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Therapeutic Exosomes in Prognosis and Developments of Coronary Artery Disease

Frontiers in Cardiovascular Medicine ◽

10.3389/fcvm.2021.691548 ◽

2021 ◽

Vol 8 ◽

Author(s):

Ai-Qun Chen ◽

Xiao-Fei Gao ◽

Zhi-Mei Wang ◽

Feng Wang ◽

Shuai Luo ◽

...

Keyword(s):

Coronary Artery Disease ◽

Coronary Artery ◽

Cell Types ◽

Biological Functions ◽

Stent Restenosis ◽

Artery Disease ◽

Almost All ◽

Different Cell Types ◽

Insight Into ◽

Systematic Knowledge

Exosomes, with an diameter of 30~150 nm, could be released from almost all types of cells, which contain diverse effective constituent, such as RNAs, proteins, lipids, and so on. In recent years, exosomes have been verified to play an important role in mechanism, diagnosis, treatment, and prognosis of cardiovascular disease, especially coronary artery disease (CAD). Moreover, it has also been shown that exosomes derived from different cell types have various biological functions based on the cell stimulation and microenvironment. However, therapeutic exosomes are currently far away from clinical translation, despite it is full of hope. In this review, we summarize an update of the recent studies and systematic knowledge of therapeutic exosomes in atherosclerosis, myocardial infarction, and in-stent restenosis, which might provide a novel insight into the treatment of CAD and promote the potential clinical application of therapeutic exosomes.

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Low Attenuation Shock Tube: Driving Mechanism and Diaphragm Characteristics

Canadian Journal of Physics ◽

10.1139/p71-240 ◽

1971 ◽

Vol 49 (15) ◽

pp. 1982-1993 ◽

Cited By ~ 11

Author(s):

F. L. Curzon ◽

M. G. R. Phillips

Keyword(s):

Shock Wave ◽

Simple Model ◽

Shock Tube ◽

Electric Shock ◽

Strong Evidence ◽

Room Temperature ◽

Wave Motion ◽

Driving Mechanism ◽

Driver Gas ◽

Opening Process

The properties of an electric shock tube fitted with a diaphragm are examined. The diaphragm opening process and its effect on the motion of the shock wave are studied. A simple model to account for the diaphragm opening time is given and critical comparisons of theory and results with other work are made.The model works well both for shock tubes employing room temperature driver gas and also for those using heated driver gas. Furthermore, there is strong evidence that the diaphragm opening process is responsible for the accelerating phase of the shock wave motion in both types of shock tube.

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