X‐Ray Plasma Ejection Associated with an Impulsive Flare on 1992 October 5: Physical Conditions of X‐Ray Plasma Ejection

1998 ◽  
Vol 499 (2) ◽  
pp. 934-944 ◽  
Author(s):  
Masamitsu Ohyama ◽  
Kazunari Shibata
Keyword(s):  
X Ray ◽  
Physical Conditions ◽  
Impulsive Flare

Analysis of the physical conditions in a strong X-ray flare

1981 ◽  
Vol 1 (13) ◽  
pp. 239-242 ◽  
Author(s):  
B. Sylwester ◽  
J. Sylwester ◽  
J. Jakimiec ◽  
B. Valniček
Keyword(s):  
X Ray ◽  
Physical Conditions

scholarly journals Infrared Analysis of Supernova Remnants

1988 ◽  
Vol 101 ◽  
pp. 363-378 ◽  
Author(s):  
Eli Dwek
Keyword(s):  
Supernova Remnants ◽  
Infrared Emission ◽  
Infrared Analysis ◽  
Atomic Processes ◽  
Infrared Observations ◽  
X Ray ◽  
Physical Conditions ◽  
The Galaxy ◽  
Dust Grain ◽  
Astronomical Satellite

AbstractInfrared observations of supernova remnants obtained with the Infrared Astronomical Satellite provide new insights into the dynamics and energetics of the remnants, and into their interaction with the ambient interstellar medium. In most remnants the infrared emission arises from dust that is collisionally heated by the X-ray emitting gas. The infrared observations can therefore be used as a diagnostic for the physical conditions of the shocked gas. In particular, it is shown that all the prominent X-ray remnants in the Galaxy and in the LMC cool mainly by dust grain collisions instead of atomic processes.

Atomic physics calculations relevant to solar flare spectra

1991 ◽  
Vol 336 (1643) ◽  
pp. 471-484 ◽  
Keyword(s):  
Solar Flare ◽  
Atomic Physics ◽  
Solar Flares ◽  
Solar Maximum ◽  
Emission Lines ◽  
Atomic Data ◽  
Solar Maximum Mission ◽  
X Ray ◽  
Physical Conditions ◽  
Recombination Processes

Solar flare spectra in the ultraviolet and X-ray wavelength regions are rich in emission lines from highly ionized ions, formed at temperatures around 10 7 K. These lines can be used as valuable diagnostics for probing the physical conditions in solar flares. Such analyses require accurate atomic data for excitation, ionization and recombination processes. In this paper, we present a review of work which has already been carried out, in particular for the Solar Maximum Mission observations, and we look to future requirements for Solar-A .

scholarly journals Redox-Sensitive Linear and Cross-Linked Cystamine-Based Polymers for Colon-Targeted Drug Delivery: Design, Synthesis, and Characterisation

Pharmaceutics ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 461
Author(s):  
Yoke Mooi Ng ◽  
Siti Nur Aishah Mat Yusuf ◽  
Hock Ing Chiu ◽  
Vuanghao Lim
Keyword(s):  
Drug Delivery ◽  
Targeted Drug Delivery ◽  
Design Synthesis ◽  
Disulfide Linkage ◽  
X Ray ◽  
Physical Conditions ◽  
Targeted Drug ◽  
Trimesoyl Chloride ◽  
Acid Reduction ◽  
Scanning Electron

Cystamine-based polymers may help to achieve controlled and targeted drug delivery to the colon due to their susceptibility to breakage of the disulfide linkage in the low redox potential environment of the colon. In this study, two linear cystamine-based polymers with similar repeating units (LP1 and LP2) and a cross-linked cystamine-based polymer (BP) were synthesised and their kinetics and the various physical conditions underlying cystamine-based polymerisation were evaluated. In brief, N1,N6-bis(2-(tritylthio)ethyl)adipamide (2) was synthesised from the reaction of triphenylmethanol and cysteamine. Next, the trityl group of 2 was removed with trifluoroacetic acid and triethylsilane before proceeding to oxidative polymerisation of the end product, N1,N6-bis(2-mercaptoethyl)adipamide (3) to LP1. The Schotten-Bauman reaction was applied to synthesise LP2 and BP from the reaction of cystamine with adipoyl chloride or trimesoyl chloride. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and mapping showed that oxygen, nitrogen, sulfur, and carbon were homogenously distributed in the polymers, with LP2 and BP having less porous morphologies compared to LP1. Results of zinc-acetic acid reduction showed that all polymers began to reduce after 15 min. Moreover, all synthesised polymers resisted stomach and small intestine conditions and only degraded in the presence of bacteria in the colon environment. Thus, these polymers have great potential for drug delivery applications. LP2 and BP, which were synthesised using the Schotten-Bauman reaction, were more promising than LP1 for colon-targeted drug delivery.

scholarly journals Late-outburst radio flaring in SS Cyg and evidence for a powerful kinetic output channel in cataclysmic variables

2019 ◽  
Vol 490 (1) ◽  
pp. L76-L80 ◽  
Author(s):  
Rob Fender ◽  
Joe Bright ◽  
Kunal Mooley ◽  
James Miller-Jones
Keyword(s):  
Binary Systems ◽  
Energy Content ◽  
Cataclysmic Variables ◽  
Early Time ◽  
X Ray ◽  
Physical Conditions ◽  
New Radio ◽  
Total Energy Content ◽  
Optical Flux ◽  
X Ray Binaries

Abstract Accreting white dwarfs in binary systems known as cataclysmic variables (CVs) have in recent years been shown to produce radio flares during outbursts, qualitatively similar to those observed from neutron star and black hole X-ray binaries, but their ubiquity and energetic significance for the accretion flow has remained uncertain. We present new radio observations of the CV SS Cyg with Arcminute Microkelvin Imager Large Array, which show for the second time late-ouburst radio flaring, in 2016 April. This flaring occurs during the optical flux decay phase, about 10 d after the well-established early-time radio flaring. We infer that both the early- and late-outburst flares are a common feature of the radio outbursts of SS Cyg, albeit of variable amplitudes, and probably of all dwarf novae. We furthermore present new analysis of the physical conditions in the best-sampled late-outburst flare, from 2016 February, which showed clear optical depth evolution. From this we can infer that the synchrotron-emitting plasma was expanding at about 1 per cent of the speed of light, and at peak had a magnetic field of order 1 G and total energy content ≥1033 erg. While this result is independent of the geometry of the synchrotron-emitting region, the most likely origin is in a jet carrying away a significant amount of the available accretion power.

scholarly journals The Jets in Micro-Quasars and Quasars: A Comparison

2005 ◽  
Vol 13 ◽  
pp. 709-713
Author(s):  
Ralph Spencer
Keyword(s):  
Radio Galaxies ◽  
Relativistic Jets ◽  
X Ray ◽  
Physical Conditions ◽  
Similarities And Differences ◽  
X Ray Binaries ◽  
Quasars And Radio Galaxies

AbstractThe discovery of relativistic jets in radio emitting X-ray binaries in our own galaxy has led to the term ‘microquasar’ being coined for these objects. In this paper the properties of microquasars are compared with those of quasars and radio galaxies, with the aim of trying to see how the similarities and differences can inform us about the physical conditions and evolution of jets. GRS1915+105 and SS433 are also discussed in more detail.

scholarly journals Radio Halos in Merging Clusters

2002 ◽  
Vol 12 ◽  
pp. 513-515 ◽  
Author(s):  
Gabriele Giovannini ◽  
Luigina Feretti
Keyword(s):  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Diffuse Source ◽  
X Ray ◽  
Diffuse Sources ◽  
Physical Conditions ◽  
Show Evidence ◽  
Radio Halos

AbstractThe number of known diffuse radio sources in clusters of galaxies (halos and relics) has grown in recent years, making it possible to derive statistical considerations on the physical conditions of these sources and on the properties of related clusters. We will discuss the percentage of clusters with a diffuse source and will show evidence that diffuse sources are associated with X-ray luminous clusters which have undergone recent merger processes.

scholarly journals NEW INSIGHTS INTO THE SPECTRAL VARIABILITY AND PHYSICAL CONDITIONS OF THE X-RAY ABSORBERS IN NGC 4151

2016 ◽  
Vol 833 (2) ◽  
pp. 191 ◽  
Author(s):  
J. D. Couto ◽  
S. B. Kraemer ◽  
T. J. Turner ◽  
D. M. Crenshaw
Keyword(s):  
Spectral Variability ◽  
X Ray ◽  
Physical Conditions ◽  
Ngc 4151

scholarly journals Chemical modeling of the complex organic molecules in the extended region around Sagittarius B2

2021 ◽  
Vol 648 ◽  
pp. A72
Author(s):  
Yao Wang ◽  
Fujun Du ◽  
Dmitry Semenov ◽  
Hongchi Wang ◽  
Juan Li
Keyword(s):  
Physical Model ◽  
Short Duration ◽  
Organic Molecules ◽  
Chemical Modeling ◽  
Warm Up ◽  
X Ray ◽  
Physical Conditions ◽  
Extended Region ◽  
Sgr A ◽  
Complex Organic

Context. The chemical differentiation of seven complex organic molecules (COMs) in the extended region around Sagittarius B2 (Sgr B2) has been previously observed: CH2OHCHO, CH3OCHO, t-HCOOH, C2H5OH, and CH3NH2 were detected both in the extended region and near the hot cores Sgr B2(N) and Sgr B2(M), while CH3OCH3 and C2H5CN were only detected near the hot cores. The density and temperature in the extended region are relatively low in comparison with Sgr B2(N) and Sgr B2(M). Different desorption mechanisms, including photodesorption, reactive desorption, and shock heating, and a few other mechanisms have been proposed to explain the observed COMs in the cold regions. However, they fail to explain the deficiency of CH3OCH3 and C2H5CN in the extended region around Sgr B2. Aims. Based on known physical properties of the extended region around Sgr B2, we explored under what physical conditions the chemical simulations can fit the observations and explain the different spatial distribution of these seven species in the extended region around Sgr B2. Methods. We used the macroscopic Monte Carlo method to perform a detailed parameter space study. A static physical model and an evolving physical model including a cold phase and a warm-up phase were used, respectively. The fiducial models adopt the observed physical parameters except for the local cosmic ray ionization rate ζCR. In addition to photodesorption that is included in all models, we investigated how chain reaction mechanism, shocks, an X-ray burst, enhanced reactive desorption and low diffusion barriers could affect the results of chemical modeling. Results. All gas-grain chemical models based on static physics cannot fit the observations, except for the high abundances of CH3NH2 and C2H5CN in some cases. The simulations based on evolving physical conditions can fit six COMs when T ~ 30−60 K in the warm-up phase, but the best-fit temperature is still higher than the observed dust temperature of 20 K. The best agreement between the simulations and all seven observed COMs at a lower temperature T ~ 27 K is achieved by considering a short-duration ≈102 yr X-ray burst with ζCR = 1.3 × 10−13 s−1 at the early stage of the warm-up phase when it still has a temperature of 20 K. The reactive desorption is the key mechanism for producing these COMs and inducing the low abundances of CH3OCH3 and C2H5CN. Conclusions. We conclude that the evolution of the extended region around Sgr B2 may have begun with a cold, T ≤ 10 K phase followed by a warm-up phase. When its temperature reached about T ~ 20 K, an X-ray flare from the Galactic black hole Sgr A* with a short duration of no more than 100 yr was acquired, affecting strongly the Sgr B2 chemistry. The observed COMs in Sgr B2 are able to retain their observed abundances only several hundred years after such a flare, which could imply that such short-term X-rays flares occur relatively often, likely associated with the accretion activity of the Sgr A* source.

scholarly journals Comparing serial X-ray crystallography and microcrystal electron diffraction (MicroED) as methods for routine structure determination from small macromolecular crystals

IUCrJ ◽  
2020 ◽  
Vol 7 (2) ◽  
pp. 306-323 ◽  
Author(s):  
Alexander M. Wolff ◽  
Iris D. Young ◽  
Raymond G. Sierra ◽  
Aaron S. Brewster ◽  
Michael W. Martynowycz ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Structural Information ◽  
Biological Macromolecules ◽  
Structural Studies ◽  
Macromolecular Crystallography ◽  
Delivery Methods ◽  
X Ray ◽  
X Ray Crystallography ◽  
Physical Conditions ◽  
Serial Crystallography

Innovative new crystallographic methods are facilitating structural studies from ever smaller crystals of biological macromolecules. In particular, serial X-ray crystallography and microcrystal electron diffraction (MicroED) have emerged as useful methods for obtaining structural information from crystals on the nanometre to micrometre scale. Despite the utility of these methods, their implementation can often be difficult, as they present many challenges that are not encountered in traditional macromolecular crystallography experiments. Here, XFEL serial crystallography experiments and MicroED experiments using batch-grown microcrystals of the enzyme cyclophilin A are described. The results provide a roadmap for researchers hoping to design macromolecular microcrystallography experiments, and they highlight the strengths and weaknesses of the two methods. Specifically, we focus on how the different physical conditions imposed by the sample-preparation and delivery methods required for each type of experiment affect the crystal structure of the enzyme.

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