unirradiated sample
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2002 ◽  
Vol 65 (3) ◽  
pp. 515-522 ◽  
Author(s):  
IOANNIS N. SAVVAIDIS ◽  
PANAGIOTIS SKANDAMIS ◽  
KYRIAKOS A. RIGANAKOS ◽  
NIKOLAOS PANAGIOTAKIS ◽  
MICHAEL G. KONTOMINAS

The effect of gamma irradiation on the natural microflora of whole salted vacuum-packaged trout at 4 and 10°C was studied. In addition, the effectiveness of gamma irradiation in controlling Listeria monocytogenes inoculated into trout was investigated. Irradiation at doses of 0.5 and 2 kGy affected populations of bacteria, namely, Pseudomonas spp., Brochothrix thermosfacta, lactic acid bacteria, H2S-producing bacteria typical of Shewanella putrefaciens, and Enterobacteriaceae, at both 4 and 10°C. This effect was more pronounced at the higher dose (2 kGy) and the lower temperature (4°C). Pseudomonads, H2S-producing bacteria typical of S. putrefaciens, and Enterobacteriaceae showed higher sensitivity to gamma irradiation than did the rest of the microbial species. Sensory evaluation did not show a good correlation with bacterial populations. On the basis of sensory odor scores, a shelf life of 28 days (2 kGy, 4°C) was obtained for salted vacuum-packaged freshwater trout, compared with a shelf life of 7 days for the unirradiated sample. Under the same conditions, the growth of L. monocytogenes inoculated into the samples was suppressed by 2 log cycles after irradiation (2 kGy) and storage for up to 18 days at 4°C.


1995 ◽  
Vol 10 (10) ◽  
pp. 2523-2530 ◽  
Author(s):  
S.A. Khasawinah ◽  
Galina Popovici ◽  
J. Farmer ◽  
T. Sung ◽  
M.A. Prelas ◽  
...  

10B doped diamond films grown by hot filament chemical vapor deposition were neutron irradiated at moderately high fluence levels. The as-irradiated and annealed samples, along with an unirradiated sample, were analyzed using Raman spectroscopy and x-ray diffraction. It was found that a non-diamond amorphous phase was formed on irradiation. This phase transformed back to diamond on annealing. No graphite formation was observed. A comparison with nanodiamond powder was made. A similarity between irradiated diamond films and nanocrystalline diamond powder is discussed.


1991 ◽  
Vol 05 (18) ◽  
pp. 1213-1224 ◽  
Author(s):  
HONGTAO REN ◽  
LING XIAO ◽  
QING HE ◽  
YUNLU ZHOU ◽  
WEIDONG BAO ◽  
...  

We have studied the effect of the fast neutron irradiation on the critical current properties and the microstructure of Melt-Textured Growth (MTG) YBa 2 Cu 3 O 7−δ with fluences of 2.3 × 1016 n/cm 2, 1.16 × 1017 n/cm 2, and 5.8 × 1017 n/cm 2 respectively. The hysteresis loops have been measured at 77 K and 1.5 K in the applied magnetic fields between −6 T and 6 T. The irreversibility lines H(T*) were also demonstrated. The critical magnetization current density J c is up to 4.7 × 105 A/cm 2 at 77 K in the field of 0.1 T for the irradiated sample with the fluence of 1.16 × 1017 n/cm 2. It is tenfold higher than that of the unirradiated sample. This increase of J c is due to the pinning at irradiation–induced pinning centers. Much higher neutron irradiation with fluence of 5.8 × 1017 n/cm 2 is harmful to the increase of J c value because the orthorhombic structure has been transformed into the tetragonal one. The amorphous state and the cellular structures are also observed in the irradiated MTG sample.


1989 ◽  
Vol 169 ◽  
Author(s):  
L. Civale ◽  
A.D. Marwick ◽  
M.W. Mcelfresh ◽  
A.P. Malozemoff ◽  
F. Holtzberg

AbstractWe have used magnetization measurements to study the effect of proton irradiation on the critical current density of a YBaCuO single crystal. We have obtained a maximum value of 1.5x105 A/cm2 at 77 K and 1 T at a fluence of 2 x 1016 cm-2, representing a 50-fold increase with respect to the unirradiated sample.


1985 ◽  
Vol 59 ◽  
Author(s):  
J. Lennart Lindström ◽  
Bengt G. Svensson

ABSTRACTIn this review we focus on oxygen-related defects created by electron irradiation (vacancy-oxygen defects) and subsequent thermal treatments. The annealing of the vacancy-oxygen pair (VO-center) at 300–350 °C is discussed as well as results from the formation and annealing of the successors to VO, the VO2 and VO3-centers. It -s found that VO2 is formed by diffusion of a vacancy-oxygen pair to an interstitial oxygen atom. It is suggested that VO3 is formed by the diffusion of interstitial oxygen to a VO2-center (in the temperature range 450–485 °C). At continued annealing at these temperatures VO3 is transferred to a new defect VO4 by attaching one more oxygen. Simultaneously thermal donors are developing in a normal way i.e. as in an unirradiated sample. It is therefore concluded that VO2 is not an important core for thermal donors but a possible nucleus for oxygen precipitation.


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