ABSTRACT
Objective The radioactivity level in historical waste from a plant is high, and decommissioning operators may be exposed to high radiation doses. The objective of the study is to carry out a radiation safety analysis of the retrieval and conditioning of naturally occurring radioactive material (NORM) waste, put forward appropriate radiation protection measures, and minimize the exposure doses of operators. Methods The source terms of NORM waste in the temporary storehouse were analyzed; MicroShield, a point kernel integration program, was used for modeling and calculation; and radiation protection measures under decommissioning conditions were put forward based on on-site monitoring data. Results The maximum gamma dose rate calculated near the waste pile in the temporary storehouse was 313.9 μGy/h, equivalent to the monitoring level; distance decay and appropriate shielding measures significantly reduced gamma dose rates for operators. Conclusion Decommissioning sites of temporary storehouses are of great harm to operators. Measures such as shielding, isolation, remote operations, and personal protection can effectively reduce the exposure doses of operators.
ABSTRACT
Aim To investigate the selective inhibition of ethanol on muscarinic receptor-or 5-HT receptor-me-diated contractile responses in the circular smooth mus-cle strips isolated from the different regions of rat stom-ach. Methods Circular muscle strips isolated from the rat gastric fundus, body, cardia and pylorus were prepared, and the contractile responses to carbachol ( CCh ) or 5-HT were recorded. Results Ethanol (0. 000 05~0. 000 5, V/V) did not affect the contrac-tile response to CCh in circular muscle strips from the rat gastric fundus and cardia, and that to 5-HT in the strips from rat gastric fundus and body ( P >0. 05 ) . However, ethanol(0. 000 1 and 0. 000 5) significantly inhibited the Emax value of the contraction by CCh from (12. 18 ± 0. 33) g of control level to (10. 88 ± 0. 41) g and -lgEC50 value from ( 6. 33 ± 0. 05 ) of control level to (6. 12 ± 0. 06)(P <0. 05) in the strips from rat gastric body. Ethanol(0. 000 1 and 0. 000 5) also significantly inhibited the Emax value of the contraction by CCh from (2. 87 ± 0. 15) g of control level to (2. 2 ± 0. 13) g and -lgEC50 value from (6. 49 ± 0. 10) of control level to (6. 05 ± 0. 09)(P<0. 01) in the strips from rat gastric pylorus. Moreover, ethanol ( 0. 000 1 and 0. 000 5) significantly inhibited the Emax value of the contraction by 5-HT from (2. 93 ± 0. 35) g of con-trol level to ( 2. 1 ± 0. 30 ) g ( P<0. 05 ) , but did not affect the -lgEC50 value in the strips from rat gastric cardia. Conclusions Ethanol inhibits the contractile responses to 5-HT only in the circular muscle strips of rat gastric cardia, and it inhibits the contractile respon-ses to CCh more strongly in the circular muscle strips of gastric pylorus than gastric body. In those gastric circular muscle strips, ethanol decreases both the ac-tivity and affinity of CCh to muscarinic receptors, but decreases only the activity of 5-HT to its receptors.
ABSTRACT
Aim To investigate the role of endothe-lium in the enhancement of phenylephrine-mediated vasoconstriction by bupivacaine in the isolated rat aor-ta.Methods The isolated rat aortic rings were pre-pared, and the vascular endothelium was removed chemically or physically .Phenylephrine-mediated vas-oconstriction was recorded .Results A pretreatment with bupivacaine at 30 μmol · L-1 for 20 min signifi-cantly increased the Emax value of vasoconstrictive re-sponses to phenylephrine from 2.22 ±0.07 g of sol-vent-controlled group to 2.50 ±0.05 g ( P0.05 ) .A pretreatment with bupivacaine at 30 μmol · L-1 for 20 min slightly but significantly inhibited the vasoconstrictive responses to low concen-tration of phenylephrine in the isolated endothelium-de-nuded rat aorta (P0.05 ) .Conclusion Bupivacaine enhances α1-adre-noceptor-mediated vasoconstriction by inhibiting vascu-lar endothelium in the isolated endothelium-intact rat aorta, Which potentiates indirectly the vasoconstrictive responses to phenylephrine .