Search results for "RADIATION"
showing 10 items of 5298 documents
Änderungen der Gitterstruktur hochpolymerer Einkristalle durch Bestrahlung im Elektronenmikroskop
1965
Die durch Bestrahlung mit Elektronen von 40 bis 80 kV hervorgerufenen Anderungen der Gitterstruktur von Polyathylen(PA)- und Polyoxymethylen(POM)-Einkristallen wurden unterrsucht. Dazu wurden Lage, Intensitat und Linienbreite der Reflexe im Elektronenbeugungsdiagramm in Abhangigkeit von der Bestrahlungsdosis gemessen. Vergleichende Untersuchungen wurden an einem Paraffin (C28H58) durchgefuhrt. Aus den Anderungen der Linienbreite konnte geschlossen werden, das im Falle des PA durch die Vernetzung zwischen benachbarten Ketten Gitterstorungen II. Art (parakristalline Storungen) hervorgerufen werden. Sie fuhren auch zu einer betrachtlichen Aufewitung des Gitters. Im Falle des Paraffins dagegen …
Temperature-dependent EXAFS study of the local structure and lattice dynamics in cubic Y2O3
2016
The local structure and lattice dynamics in cubic Y2O3were studied at the YK-edge by X-ray absorption spectroscopy in the temperature range from 300 to 1273 K. The temperature dependence of the extended X-ray absorption fine structure was successfully interpreted using classical molecular dynamics and a novel reverse Monte Carlo method, coupled with the evolutionary algorithm. The obtained results allowed the temperature dependence of the yttria atomic structure to be followed up to ∼6 Å and to validate two force-field models.
Bone metastases in soft tissue sarcoma patients: A survey of natural, prognostic value, and treatment.
2012
10063 Background: Given the limited data currently available, we surveyed the natural history of bone metastases in patients affected by soft tissue sarcoma (STS). Methods: This retrospective, multicenter, observational study evaluated data from 135 patients with STS metastatic to the bone who presented between 2001 and 2011. For all patients, we recorded the primary tumor histological subtype, bone metastases characteristics (onset, site), type of treatment received (surgery, radiotherapy, zoledronic acid), type and frequency of skeletal related events (SRE) and disease outcome. Results: The most represented histological subtypes among the enrolled patients were leiomyosarcoma (27%), angi…
Safety and efficacy of intensity-modulated radiotherapy in the management of spermatic cord sarcoma.
2017
International audience; Purpose. - Spermatic cord sarcoma is a rare disease, which management remains controversial due to the lack of guidelines. The standard therapeutic approach is surgical: wide soft-tissue resection with radical inguinal orchidectomy, The diagnosis is made during the analysis of the specimen. The high rate of local recurrence indicates adjuvant radiotherapy of the tumor bed. The aim of this series is to determine the efficacy and safety of postoperative intensity-modulated radiotherapy for spermatic cord sarcomas. Patients and methods. - Our series included five consecutive cases of spermatic cord sarcoma treated between 2011 and 2014. The indications for radiotherapy …
Determination of scattering in intraocular lenses by spectrophotometric measurements.
2014
This study presents a method for measuring scattering in explanted intraocular lenses (IOLs). Currently, determining scattering in IOLs is usually performed by Scheimpflug cameras and the results are expressed in the units used by this apparatus. The method we propose uses a spectrophotometer and this makes it possible to measure the total transmission of the IOL by using an integrating sphere; the direct transmission is determined by the double-beam mode. The difference between these two transmissions gives a value of the scattering in percentage values of light lost. In addition, by obtaining the spectral transmission curve, information about the most scattered wavelengths is also obtaine…
Radiācijas defektu pētījumi ar EPR metodi LiBaF3 kristālā
2004
Izpētīts ar rentgenu istabas temperatūrā apstarotā L i B a F 3 kristālā radīta defekta EPR spektrs. EPR spektrs sastāv no apmēram 35 ekvidistantām līnijām. Defekts ir nestabils Jienas gaismā, bet tumsā sabrūk dažu stundu laikā. Šīs līnijas magnētiskā lauka orientācijā mralēli [111] kristāla asij atrodas vienādos attālumos (ar soli 0,9 mT) ar intensitāšu sadalījumu tuvu binomiālajam. EPR spektru var aprakstīt kā nesapārota spina S = 1/2 hiper- >īkstruktūras (liss) mijiedarbību ar divām ekvivalentu kaimiņu kodolu spinu grupām: 2 Li kodoliem pirmajā grupā un 8 F kodoliem otrajā grupā. Šāds modelis atbilst F-tipa centram elektrons atrodas fluora vakancē) LiBaF3 kristālā. Līniju intensitāšu stip…
Time-variations of zeroth-order vegetation absorption and scattering at L-band
2021
Abstract Surface soil moisture and vegetation optical depth (VOD), as an indicator of vegetation wet biomass, from passive microwave remote sensing have been increasingly applied in global ecology and climate research. Both soil moisture and VOD are retrieved from satellite brightness temperature measurements assuming a zeroth order radiative transfer model, commonly known as the tau-omega model. In this model the emission of a vegetated surface is dependent on soil moisture, vegetation absorption and vegetation scattering. Vegetation scattering is normally represented by the single scattering albedo, ω, and is commonly assumed to be a time-invariant calibration parameter to achieve high ac…
Relaxation Dynamics of Cr(acac)3 Probed by Ultrafast Infrared Spectroscopy
2007
Ultrafast infrared spectroscopy is used to probe the dynamics of Cr(acac)3 upon ligand field (400 nm) and charge transfer state (345 nm) excitation. At both pump wavelengths, the ground state absorption bands are strongly bleached at zero delay, and new broad transient absorption bands appear red shifted from the bleached bands. Recovery of ground state bleach is dominated by a fast time constant (15 ps), while a small percentage recovers within 760−900 ps. Despite the extensive studies on Cr(acac)3 photophysics, the fast recovery of the ground state as a major channel is reported here for the first time. As a general result, the present communication emphasizes the great value of ultrafast…
Magnetic ordering in an (Fe0.2Cr0.8)1.5[Cr(CN)6] Prussian blue analogue studied with synchrotron radiation based spectroscopies
2018
The appearance of magnetic order in the (Fe0.2Cr0.8)1.5[Cr(CN)6]·15H2O Prussian blue analogue at low temperature has been investigated by means of synchrotron radiation-based X-ray absorption spectroscopy and X-ray magnetic circular dichroism. With the help of ligand field multiplet analysis we have been able to identify the oxidation states of the metallic cations present in the sample and their evolution with temperature. Our experiments reveal that the appearance of ferromagnetic order is triggered by the transformation of CrIII cations to CrII high-spin caused by a transfer of electrons from the Fe to the Cr resulting in an increase of the magnetic interactions within the (Cr, Cr) subla…
Light Dark Matter Search with Ionization Signals in XENON1T
2019
We report constraints on light dark matter (DM) models using ionization signals in the XENON1T experiment. We mitigate backgrounds with strong event selections, rather than requiring a scintillation signal, leaving an effective exposure of (22±3) tonne day. Above ∼0.4 keVee, we observe <1 event/(tonne day keVee), which is more than 1000 times lower than in similar searches with other detectors. Despite observing a higher rate at lower energies, no DM or CEvNS detection may be claimed because we cannot model all of our backgrounds. We thus exclude new regions in the parameter spaces for DM-nucleus scattering for DM masses mχ within 3–6 GeV/c2, DM-electron scattering for mχ>30 MeV/c2, a…