Iodine Volume Diffusion Measurements in Uranium Dioxide

2012 ◽  
Vol 323-325 ◽  
pp. 197-202 ◽  
Author(s):  
E. Pizzi ◽  
Philippe Garcia ◽  
G. Carlot ◽  
H. Palancher ◽  
S. Maillard ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Concentration Profile ◽  
Volume Diffusion ◽  
Back Scattering ◽  
Grain Orientations ◽  
Profile Changes ◽  
Secondary Ion ◽  
Iodine Diffusion

The presence of iodine in UO2has a great impact on nuclear fuel behaviour, both during-in reactor operation or under long-term repository conditions. Here the volume diffusion coefficient of iodine is studied using a methodology which involves ion implantation, annealing under different oxygen potentials and SIMS (Secondary Ion Mass Spectroscopy) for the concentration profile characterization of samples. The changes in the initial concentration profile induced by annealing are interpreted using Ficks second law to determine the diffusion coefficient. The first part of this paper is devoted to the description of the applied methodology. The iodine diffusion coefficients in the bulk are shown to depend upon the annealing temperature and oxygen potential. In smaller grained polycrystalline samples, the SIMS signal is averaged out over several grains and therefore, the analysis of the depth profile changes in samples due to annealing may be efficiently compared to depth profiles in as-implanted samples. By contrast, in Cr-doped UO2samples in which the grain size is larger than the zone analysed by SIMS, a particular methodology has to be developed. To this end, large grained material was examined using EBSD (Electron Back Scattering Diffraction) in order to determine the relative crystalline orientations of the grains. Following iodine implantations, various grains with different orientations were studied using SIMS. An attempt is presented at correlating the different sputtering rates with the various grain orientations.

Assessing the Power of Electron Back Scattering Diffraction Characterization of Deformed F-138 Steel from the View Point of Crystal Diffraction

2014 ◽  
Vol 51 (9) ◽  
pp. 634-655
Author(s):  
R. E. Bolmaro ◽  
M. C. Avalos ◽  
N. S. De Vincentis ◽  
A. M. Kliauga ◽  
H.-G. Brokmeier
Keyword(s):  
View Point ◽  
Back Scattering

Characterization and Elimination of Forward Snapback Defects in GaAs Light Emitting Diodes

1996 ◽  
Author(s):  
J. Zimmer ◽  
D. Nielsen ◽  
T.A. Anderson ◽  
M. Schade ◽  
N. Saha ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Light Emitting Diode ◽  
Elevated Concentration ◽  
Forward Voltage ◽  
Light Emitting ◽  
Intermittent Yield ◽  
Si Doped ◽  
Secondary Ion ◽  
Furnace Pressure

Abstract The p-n junction of a GaAs light emitting diode is fabricated using liquid phase epitaxy (LPE). The junction is grown on a Si doped (~1018/cm3) GaAs substrate. Intermittent yield loss due to forward voltage snapback was observed. Historically, out of specification forward voltage (Vf) parameters have been correlated to abnormalities in the junction formation. Scanning electron (SEM) and optical microscopy of cleaved and stained samples revealed a continuous layer of material approximately 2.5 to 3.0 urn thick at the n-epi/substrate interface. Characterization of a defective wafer via secondary ion mass spectroscopy (SIMS) revealed an elevated concentration of O throughout the region containing the defect. X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) data taken from a wafer prior to growth of the epi layers did not reveal any unusual oxidation or contamination. Extensive review of the processing data suggested LPE furnace pressure was the obvious source of variability. Processing wafers through the LPE furnace with a slight positive H2 gas pressure has greatly reduced the occurrence of this defect.

scholarly journals Characterization of Highly Irradiated ALPIDE Silicon Sensors

Universe ◽  
2019 ◽  
Vol 5 (4) ◽  
pp. 91
Author(s):  
Valentina Raskina ◽  
Filip Křížek
Keyword(s):  
Nuclear Physics ◽  
Detection Efficiency ◽  
Tracking System ◽  
Physics Institute ◽  
Total Ionization ◽  
Silicon Sensors ◽  
Active Pixel ◽  
Academy Of Sciences

The ALICE (A Large Ion Collider Experiment) experiment at CERN will upgrade its Inner Tracking System (ITS) detector. The new ITS will consist of seven coaxial cylindrical layers of ALPIDE silicon sensors which are based on Monolithic Active Pixel Sensor (MAPS) technology. We have studied the radiation hardness of ALPIDE sensors using a 30 MeV proton beam provided by the cyclotron U-120M of the Nuclear Physics Institute of the Czech Academy of Sciences in Řež. In this paper, these long-term measurements will be described. After being irradiated up to the total ionization dose 2.7 Mrad and non-ionizing energy loss 2.7 × 10 13 1 MeV n eq · cm - 2 , ALPIDE sensors fulfill ITS upgrade project technical design requirements in terms of detection efficiency and fake-hit rate.

Characterization of New Ionically Conducting Peo-Based Networks by Diffusion, Elasticity Modulus and Ionic Conductivity Measurements

1992 ◽  
Vol 293 ◽  
Author(s):  
Herve Cheradame ◽  
F. Desbat ◽  
P. Mercier-Niddam ◽  
S. Boileau
Keyword(s):  
Diffusion Coefficient ◽  
Ionic Conductivity ◽  
Elasticity Modulus ◽  
Sol Gel ◽  
Cation Transport ◽  
Lithium Cation ◽  
Conductivity Measurements ◽  
Conducting Materials ◽  
Diffusion Studies

AbstractIonically conducting materials containing PEO were prepared from telechelic di(methyl-diethoxy-silane) PEO, synthesized by the hydrosilylation of telechelic diallyl-PEO with methyldiethoxysilane. The network is obtained by the usual sol-gel chemistry. Then, it is filled with LiClO4 by diffusion of the salt and further drying. A comparison is made with the same kind of materials crosslinked using urethane chemistry. Diffusion studies show that the diffusion coefficient of solvent is similar for both types of materials, whilst the ionic conductivity is higher for the networks crosslinked with siloxane bonds. An experiment of diffusion of LiClO4 without solvent showed that this salt has a diffusion coefficient of the order of 2.10-8 cm2.sec-1 at 34°C. The conductivity calculated from this determination is compatible with the mechanism of lithium cation transport by the diffusion of salt molecules. Elasticity modulus measurements show that the salt aggregates are essentially located within the crosslinks at low concentration, but also in the PEO chains for salt concentrations higher than 1 mol/l.

Post-Operative Dysphagia in Anterior Cervical Discectomy and Fusion

2021 ◽  
pp. 000348942110155
Author(s):  
Leonard Haller ◽  
Khush Mehul Kharidia ◽  
Caitlin Bertelsen ◽  
Jeffrey Wang ◽  
Karla O’Dell
Keyword(s):  
Risk Factors ◽  
Medical Records ◽  
Assessment Tool ◽  
Demographic Data ◽  
Anterior Cervical Discectomy ◽  
Cervical Discectomy ◽  
Long Term Follow Up

Objective: We sought to identify risk factors associated with long-term dysphagia, characterize changes in dysphagia over time, and evaluate the incidence of otolaryngology referrals for patients with long-term dysphagia following anterior cervical discectomy with fusion (ACDF). Methods: About 56 patients who underwent ACDF between May 2017 to February 2019 were included in the study. All patients were assessed for dysphagia using the Eating Assessment Tool (EAT-10) survey preoperatively and late postoperatively (≥1 year). Additionally, 28 patients were assessed for dysphagia early postoperatively (2 weeks—3 months). Demographic data, medical comorbidities, intraoperative details, and post-operative otolaryngology referral rates were collected from electronic medical records. Results: Of the 56 patients enrolled, 21 patients (38%) had EAT-10 scores of 3 or more at long-term follow-up. None of the demographics, comorbidities, or surgical factors assessed were associated with long-term dysphagia. Patients who reported no long-term dysphagia had a mean EAT-10 score of 6.9 early postoperatively, while patients with long-term symptoms had a mean score of 18.1 ( P = .006). Of the 21 patients who reported persistent dysphagia symptoms, 3 (14%) received dysphagia testing or otolaryngology referrals post-operatively. Conclusion: Dysphagia is a notable side effect of ACDF surgery, but there are no significant demographics, comorbidities, or surgical risk factors that predict long-term dysphagia. Early postoperative characterization of dysphagia using the EAT-10 questionnaire can help predict long-term symptoms. There is inadequate screening and otolaryngology follow-up for patients with post-ACDF dysphagia.

scholarly journals Clinical characterization of 266 patients and family members with cleft lip and/or palate with associated malformations and syndromes

2021 ◽  
Author(s):  
Theodosia Bartzela ◽  
Björn Theuerkauf ◽  
Elisabeth Reichardt ◽  
Malte Spielmann ◽  
Charlotte Opitz
Keyword(s):  
Early Identification ◽  
Congenital Malformations ◽  
Cleft Lip ◽  
Phenotypic Variability ◽  
Family Members ◽  
Pierre Robin Sequence ◽  
Associated Malformations ◽  
Pierre Robin

Abstract Objectives To clinically characterize patients and family members with cleft lip and/or palate (CL/P) and associated congenital malformations or syndromes and propose possible inheritance patterns. Materials and methods An observational study of patients with CL/P, including medical and family history and intra- and extra-oral examination of their family members, was performed. Results Two hundred sixty-six patients, 1257 family members, and 42 pedigrees were included in the study. The distribution of patients according to the cleft type was 57.9% with CLP, 25.2% with cleft palate (CPO), and 12.8% with cleft lip with/without alveolus (CL/A). Seventy-four (27.8%) patients had associated malformations, and 24 (9.2%) a syndrome. The skeletal (27.7%), cardiovascular (19.3%) systems, and eyes (22.9%) were most commonly affected. Pierre Robin Sequence (7 patients) and van der Woude (4) were the most common syndromes. The majority of patients with CPO (19/24) had an associate syndrome. The families had an average of 2.45 affected members. Conclusion Individual and interfamilial phenotypic variability in patients with CL/P makes the understanding of etiopathogenesis challenging. Clinical relevance The overall prevalence of individuals with CL/P and their pedigrees with associated malformations and syndromes emphasize the need for early identification, interdisciplinary, and long-term planning.

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