Models and regressions to describe primary damage in silicon carbide.

Silicon carbide (SiC) and SiC/SiC composites are important candidate materials for use in the nuclear industry. Coarse grain models are the only tools capable of modelling defect accumulation under different irradiation conditions at a realistic time and length scale. The core of any such model is the so-called "source term", which is described by the primary damage. In the present work, classical molecular dynamics (MD), binary collision approximation (BCA) and NRT model are applied to describe collision cascades in 3C-SiC with primary knock-on atom (PKA) energy in the range 1-100 keV. As such, BCA and NRT are benchmarked against MD. Particular care was taken to account for electronic stopping and the use of a threshold displacement energy consistent with density functional theory and experiment. Models and regressions are developed to characterize the primary damage in terms of number of stable Frenkel pairs and their cluster size distribution, anti-sites, and defect type. As such, an accurate cascade database is developed with simple descriptors. One of the main results shows that the defect cluster size distribution follows the geometric distribution rather than a power law.

Periosteal chondroma of the proximal radius: a case report.

When a chondroma is localized in the superficial region of the bone it is defined periosteal or juxtacortical chondroma. This is a rare and benign cartilaginous lesion that more frequently affects males, and is generally observed in the tubular bones of the hand; it may, however, affect the other major bones, particularly the proximal end of the humerus. Age of onset is the second or third decade of life. Symptoms include moderate local pain. The clinical case presented here has two special features: the first is the site; based on an analysis of the international literature it seems that an analogous lesion at the level of the radial neck has not as yet been described; the second is the symptomatology that brought the patient to our attention.

Development, morphology, and progression of mammary tumors during and after fertile life in BALB/cfRIII mice.

A study was done on 368 BALB/cfRIII mammary tumor-bearing breeding female mice that are of the BALB/c genotype and carry milk-transmitted RIII murine mammary tumor virus (MuMTV) infection initiated by foster-nursing. All tumors were characterized by chronologic, biologic, and morphologic analyses. Mammary tumors occurring during pregnancy-lactation periods were mostly pregnancy-dependent plaques showing organoid tubular structure, sudden growth during late pregnancy, regression after delivery, and slow progression. The frequency of pregnancy-dependent tumors per 100 mice at risk increased steadily from first (1 tumor) to sixth (38 tumors) pregnancy-lactation period. Mammary tumors occurring after fertile life were mostly characterized by an irregular, slow growth and a type B morphology. The frequency of these tumors per 100 mice at risk per 100 days of survival also increased regularly in females undergoing from one (73 tumors) to six (117 tumors) pregnancy-lactation periods. Data were discussed in the light of the pattern of MuMTV release through BALB/cfRIII milk.