The Role of Contrast Barium X-Rays vs. Endoscopy

1996 ◽  
pp. 141-160
Keyword(s):  
X Rays

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

Reactive oxygen species in cell responses to toxic agents

2002 ◽  
Vol 21 (2) ◽  
pp. 85-90 ◽  
Author(s):  
L E Feinendegen
Keyword(s):  
Radiation Exposure ◽  
Mammalian Cells ◽  
Low Dose ◽  
X Rays ◽  
Low Dose Radiation ◽  
Cell Responses ◽  
Toxic Agents ◽  
Particle Tracks ◽  
Dose Radiation

This review first summarizes experimental data on biological effects of different concentrations of ROS in mammalian cells and on their potential role in modifying cell responses to toxic agents. It then attempts to link the role of steadily produced metabolic ROS at various concentrations in mammalian cells to that of environmentally derived ROS bursts from exposure to ionizing radiation. The ROS from both sources are known to both cause biological damage and change cellular signaling, depending on their concentration at a given time. At low concentrations signaling effects of ROS appear to protect cellular survival and dominate over damage, and the reverse occurs at high ROS concentrations. Background radiation generates suprabasal ROS bursts along charged particle tracks several times a year in each nanogram of tissue, i.e., average mass of a mammalian cell. For instance, a burst of about 200 ROS occurs within less than a microsecond from low-LET irradiation such as X-rays along the track of a Compton electron (about 6 keV, ranging about 1 μm). One such track per nanogram tissue gives about 1 mGy to this mass. The number of instantaneous ROS per burst along the track of a 4-meV ¬-particle in 1 ng tissue reaches some 70000. The sizes, types and sites of these bursts, and the time intervals between them directly in and around cells appear essential for understanding low-dose and low dose-rate effects on top of effects from endogenous ROS. At background and low-dose radiation exposure, a major role of ROS bursts along particle tracks focuses on ROS-induced apoptosis of damage-carrying cells, and also on prevention and removal of DNA damage from endogenous sources by way of temporarily protective, i.e., adaptive, cellular responses. A conclusion is to consider low-dose radiation exposure as a provider of physiological mechanisms for tissue homoeostasis.

scholarly journals AGN surveys to study galaxy evolution along cosmic times

2013 ◽  
Vol 9 (S304) ◽  
pp. 180-186
Author(s):  
Luigi Spinoglio
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Energy Production ◽  
X Rays ◽  
Radio Frequencies ◽  
Ir Spectroscopic ◽  
Observational Techniques ◽  
Production Mechanisms

AbstractVarious observational techniques have been used to survey galaxies and AGN, from X-rays to radio frequencies, both photometric and spectroscopic. I will review these techniques aimed at the study of galaxy evolution and of the role of AGNs and star formation as the two main energy production mechanisms. I will then present as a new observational approach the far-IR spectroscopic surveys that could be done with planned astronomical facilities of the next future, such as SPICA from the space and CCAT from the ground.

Follow up of low grade sarcoma: The role of chest X-rays

2014 ◽  
Vol 67 (6) ◽  
pp. 882-884
Author(s):  
J.K. O'Neill ◽  
I. Gregory ◽  
C. McArdle ◽  
H. Taha ◽  
C. Millman ◽  
...  
Keyword(s):  
Low Grade ◽  
X Rays

Role of diagnostic imaging in diagnosis by Covid-19

2020 ◽  
Author(s):  
Coda Marco ◽  
Sica Federica ◽  
Finelli Mirko ◽  
Ungaro Gaetano ◽  
Sica Alfonso Marco
Keyword(s):  
Differential Diagnosis ◽  
Lung Parenchyma ◽  
Chest Ct ◽  
Initial Assessment ◽  
X Rays ◽  
Radiological Imaging ◽  
Laboratory Examinations ◽  
Clinical Conditions

The diagnosis from Covid-19 provides the set of several examinations such as: clinical examinations, laboratory examinations, radiographic examinations. Using radiological imaging, RX and chest CT, it is possible to evaluate the impairment of lung function and thanks to this aspect it is possible to define the severity and clinical conditions of the patient. In this way, it allows timely therapeutic intervention especially if the patient shows a mild condition in such a way as to avoid the onset of further complications. Chest X-rays allow both an initial assessment of patients and the possibility to perform a differential diagnosis towards other possible causes of lung parenchyma involvement. The CT scan, which highlights the peculiar characteristics of COVID pneumonia, is performed both as diagnostic confirmation and in the patient’s follow-up.

scholarly journals Monkeypox Virus in Nigeria: Infection Biology, Epidemiology, and Evolution

Viruses ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1257
Author(s):  
Emmanuel Alakunle ◽  
Ugo Moens ◽  
Godwin Nchinda ◽  
Malachy Ifeanyi Okeke
Keyword(s):  
Reservoir Host ◽  
Recent Common Ancestor ◽  
Future Research ◽  
Gene Gain ◽  
X Rays ◽  
Host Animal ◽  
Monkeypox Virus ◽  
Most Recent Common Ancestor ◽  
Infection Biology

Monkeypox is a zoonotic disease caused by monkeypox virus (MPXV), which is a member of orthopoxvirus genus. The reemergence of MPXV in 2017 (at Bayelsa state) after 39 years of no reported case in Nigeria, and the export of travelers’ monkeypox (MPX) from Nigeria to other parts of the world, in 2018 and 2019, respectively, have raised concern that MPXV may have emerged to occupy the ecological and immunological niche vacated by smallpox virus. This review X-rays the current state of knowledge pertaining the infection biology, epidemiology, and evolution of MPXV in Nigeria and worldwide, especially with regard to the human, cellular, and viral factors that modulate the virus transmission dynamics, infection, and its maintenance in nature. This paper also elucidates the role of recombination, gene loss and gene gain in MPXV evolution, chronicles the role of signaling in MPXV infection, and reviews the current therapeutic options available for the treatment and prevention of MPX. Additionally, genome-wide phylogenetic analysis was undertaken, and we show that MPXV isolates from recent 2017 outbreak in Nigeria were monophyletic with the isolate exported to Israel from Nigeria but do not share the most recent common ancestor with isolates obtained from earlier outbreaks, in 1971 and 1978, respectively. Finally, the review highlighted gaps in knowledge particularly the non-identification of a definitive reservoir host animal for MPXV and proposed future research endeavors to address the unresolved questions.

scholarly journals The role of intracellular oxidation in death induction (apoptosis and necrosis) in human promonocytic cells treated with stress inducers (cadmium, heat, X-rays)

2001 ◽  
Vol 80 (4) ◽  
pp. 312-320 ◽  
Author(s):  
Alba Galán ◽  
Laura García-Bermejo ◽  
Alfonso Troyano ◽  
Nuria E. Vilaboa ◽  
Carlos Fernández ◽  
...  
Keyword(s):  
X Rays ◽  
Apoptosis And Necrosis ◽  
Promonocytic Cells

On the role of radioactive decays in powering gamma rays and X-rays from novae

1992 ◽  
Vol 394 ◽  
pp. 217 ◽  
Author(s):  
Mario Livio ◽  
Apostolos Mastichiadis ◽  
Hakki Oegelman ◽  
James W. Truran
Keyword(s):  
Gamma Rays ◽  
X Rays
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