METHODS FOR PREPROCESSING TOMOGRAPHIC IMAGES TAKING INTO ACCOUNT THE THERMAL INSTABILITY OF THE X-RAY TUBE

2019 ◽  
Keyword(s):  
Thermal Instability ◽  
Tomographic Images ◽  
X Ray

A 35-year-old mystery solved: a facile synthetic route and structural confirmation of tetrachlorobis(diethyl ether)tungsten(IV)

2021 ◽  
Vol 77 (4) ◽  
Author(s):  
Thomas E. Shaw ◽  
Alfred P. Sattelberger ◽  
Titel Jurca
Keyword(s):  
Crystal Structure ◽  
Diethyl Ether ◽  
Thermal Instability ◽  
Room Temperature ◽  
Surface Characteristics ◽  
Hirshfeld Surface ◽  
Asymmetric Unit ◽  
Synthetic Route ◽  
X Ray ◽  
Elemental Analyses

The true identity of the diethyl ether adduct of tungsten(IV) chloride, WCl4(Et2O) x , has been in doubt since 1985. Initially postulated as the bis-adduct, WCl4(Et2O)2, questions arose when elemental analyses were more in line with a mono-ether adduct, viz. WCl4(Et2O). It was proposed that this was due to the thermal instability of the bis-adduct. Here, we report the room-temperature X-ray crystal structure and Hirshfeld surface characteristics of trans-tetrachloridobis(diethyl ether)tungsten(IV), trans-WCl4(Et2O)2 or trans-[WCl4(C4H10O)2]. The compound crystallizes, with half of the molecule in the asymmetric unit, in the centrosymmetric space group P21/n. The W—O distance is 2.070 (2) Å, while the W—Cl distances are 2.3586 (10) and 2.3554 (10) Å.

scholarly journals Thermal instability in X-ray photoionized media in active galactic nuclei

2009 ◽  
Vol 499 (1) ◽  
pp. 349-355 ◽  
Author(s):  
B. Czerny ◽  
L. Chevallier ◽  
A. C. Gonçalves ◽  
A. Różańska ◽  
A.-M. Dumont
Keyword(s):  
Active Galactic Nuclei ◽  
Thermal Instability ◽  
Galactic Nuclei ◽  
X Ray

scholarly journals Ultrasonic Mammography with Circular Transducer Array

2015 ◽  
Vol 39 (4) ◽  
pp. 559-568
Author(s):  
Krzysztof J. Opieliński ◽  
Piotr Pruchnicki ◽  
Tadeusz Gudra
Keyword(s):  
Ultrasonic Transducer ◽  
Measurement Data ◽  
Projection Methods ◽  
Vertical Movement ◽  
Transducer Array ◽  
Tomographic Images ◽  
X Ray ◽  
Complementary Method ◽  
Breast Phantom ◽  
Set Up

Abstract Ultrasonic projection imaging is similar to X-ray radiography. Nowadays, ultrasonic projection methods have been developed in the set-up of multi-element flat arrays with miniature transducers, where one of the array acts as a transmitter and the other one is a receiver. In the paper, a new method of the projection imaging using a 1024-element circular ultrasonic transducer array is presented. It allows the choice of a projection scanning plane for any angle around a studied object submerged in water. Fast acquisition of measurement data is achieved as a result of parallel switching of opposite transmitting and receiving transducers in the circular array and vertical movement of the array. The algorithm equalizing the length of measurement rays and the distances between them was elaborated for the reconstruction of projection images. Projection research results of breast phantom obtained by means of the elaborated measurement set-up and compared with mammography simulations (acquired through overlapping of X-ray tomographic images) show that ultrasonic projection method presented in this paper (so-called ultrasonic mammogra-phy) can be applied to the woman's breast and be used as a diagnosis for an early detection of cancerous lesions. It can, most of all, be used as an alternative or complementary method to standard mammography, which is harmful because of ionizing radiation and invasive due to the mechanical compression of tissue.

scholarly journals Warm and thick corona for a magnetically supported disk in galactic black hole binaries

2020 ◽  
Vol 633 ◽  
pp. A35 ◽  
Author(s):  
D. Gronkiewicz ◽  
A. Różańska
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Accretion Disk ◽  
Thermal Instability ◽  
Stellar Mass ◽  
Rotational Instability ◽  
X Ray ◽  
Black Hole Binaries ◽  
Radiative Processes ◽  
Gas Heating

Context. We self-consistently model a magnetically supported accretion disk around a stellar-mass black hole with a warm optically thick corona based on first principles. We consider the gas heating by magneto-rotational instability dynamo. Aims. Our goal is to show that the proper calculation of the gas heating by magnetic dynamo can build up the warm optically thick corona above the accretion disk around a black hole of stellar mass. Methods. Using the vertical model of the disk supported and heated by the magnetic field together with radiative transfer in hydrostatic and radiative equilibrium, we developed a relaxation numerical scheme that allowed us to compute the transition form the disk to corona in a self-consistent way. Results. We demonstrate here that the warm (up to 5 keV) optically thick (up to 10 τes) Compton-cooled corona can form as a result of magnetic heating. A warm corona like this is stronger in the case of the higher accretion rate and the greater magnetic field strength. The radial extent of the warm corona is limited by local thermal instability, which purely depends on radiative processes. The obtained coronal parameters are in agreement with those constrained from X-ray observations. Conclusions. A warm magnetically supported corona tends to appear in the inner disk regions. It may be responsible for soft X-ray excess seen in accreting sources. For lower accretion rates and weaker magnetic field parameters, thermal instability prevents a warm corona, giving rise to eventual clumpiness or ionized outflow.

scholarly journals Anatomy description of cervical region and hyoid apparatus in living giant anteaters Myrmecophaga tridactyla Linnaeus, 1758

2017 ◽  
Vol 37 (11) ◽  
pp. 1345-1351
Author(s):  
Naida C. Borges ◽  
João R.B. Nardotto ◽  
Raquel S.L. Oliveira ◽  
Larissa H.E. Rüncos ◽  
Rejane G. Ribeiro ◽  
...  
Keyword(s):  
Feeding Habits ◽  
Imaging Techniques ◽  
Cervical Region ◽  
Essential Information ◽  
Tomographic Images ◽  
X Ray ◽  
Diagnosis And Prognosis ◽  
Topographical Anatomy ◽  
Anatomical Adaptations ◽  
Limited Usefulness

ABSTRACT: The giant anteater has specific anatomical adaptations resulting from its ant and termite feeding habits. The unique arrangement of its hyoid apparatus is essential for the ingestion of food. However, its description in the literature is based on fragments and fossils, making it difficult to determine existing anatomical details in live animals. Imaging techniques, which enable the topographical anatomy of animals to be examined noninvasively, provide essential information for the diagnosis and prognosis of diseases. The aim of this study is to describe the bone contours in the hyoid apparatus of the giant anteater by means of radiographic and tomographic images. Giant anteaters of varying ages from the Wild Animal Screening Center (CETAS-GO) were used, seven for X-ray exams and two adults for CT exams. The hyoid elements in all the animals were evaluated using the two imaging techniques, and were visualized in the cervical region of C2 to C6, which comprises three paired bones (stylohyoid, epihyoid, ceratohyoid) and one unpaired bone (basihyoid). The presence of air in the oropharynx enabled the assessment of soft tissue structures in this region, such as the epiglottis and the soft palate. CT axial sections are of limited usefulness for evaluating the hyoid bones, but enable assessments of the basihyoid bone and its characteristic V-shape. Thus, to analyze the hyoid region in anteaters based on radiographic and tomographic images, one must keep in mind that the stylohyoid, epihyoid and ceratohyoid bones are situated ventrally to the C2 to C5 vertebrae and that the basihyoid at the level of C5-C6 demarcates the transition between the nasopharynx and the trachea. The nasopharynx and oropharynx extend from C1 to C5, and the trachea begins at the level of C6.

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