RESUMO
The synergistic effects on the 0.18 µm PPD CISs induced by neutron displacement damage and gamma ionization damage are investigated. The typical characterizations of the CISs induced by the neutron displacement damage and gamma ionization damage are presented separately. The CISs are irradiated by reactor neutron beams up to 1 × 1011 n/cm2 (1 MeV neutron equivalent fluence) and 60Co γ-rays up to the total ionizing dose level of 200 krad(Si) with different sequential order. The experimental results show that the mean dark signal increase in the CISs induced by reactor neutron radiation has not been influenced by previous 60Co γ-ray radiation. However, the mean dark signal increase in the CISs induced by 60Co γ-ray radiation has been remarkably influenced by previous reactor neutron radiation. The synergistic effects on the PPD CISs are discussed by combining the experimental results and the TCAD simulation results of radiation damage.
RESUMO
OBJECTIVE: To study the mechanism of brain development delay in rats with intrauterine growth retardation (IUGR) by examining the expression of nerve growth factor (NGF) and tyrosine kinase receptor A (Trk A) in the brain. METHODS: Thirty-two pregnant rats were randomly fed with a normal diet (control group) or lower protein diet (IUGR group) during pregnancy (n=16 each). The pup rats were sacrificed at 0, 7, 14 or 21 days after birth. The protein levels of NGF and TrkA in the brain were determined by Western blot and immunohistochemistry staining. RESULTS: The levels of NGF and TrkA in the brain in pup rats of the IUGR group were significantly lower than those in the control group 0, 7, 14 and 21 days after birth. CONCLUSIONS: The decreased expression of protein levels of NGF and TrkA in the brain might be one of the causes of brain development delay in IUGR rats.