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Objective To establish an effective and reliable method for analysis of uhratrace uranium in multi-stage atmospheric particles providing the monitoring and evaluation of the content of radioactive uranium in the atmosphere.Methods A large volume six-stage-impactor sampler of atmosphere particles was used to collect aerosol samples,and uhratrace uranium in particles was digested using microwave and measured by inductively coupled plasma mass spectrometry.The filter material,digestion conditions and microwave digestion system had been optimized.Results The background of uranium level on the cellulose filter was the lowest,and the samples were digested by using HNO3-HCI (aqua regia)-H2O2 solution.Reference material SRM2783 was used to validate the accuracy of the method,and the relative error of the 238U was 7％,The detection limit of the method was 2 × 10-4ng/m3.The aerosol actual samples were analyzed using the established method.The mass concentrations of uranium in PM2.5 was in the range of 0.023-0.065 ng/m3.Conclusions The established method was effective and reliable to monitor the concentration level of ultratrace uranium in multi-stage atmospheric particles.
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Objective To investigate the activity concentration of 90St in tea produced in Chinese typical regions,enrich the baseline data for 90Sr level in Chinese tea,and evaluate possible exposure doses to people.Methods Samples were carbonized,ashed,digested and leached,and then extraction chromatography method was used to separate 90Sr and 90y.After preparation of sample source,radioactivity of 90Y was measured using low-level α/β counter.Results Twenty six kinds of tea produced in 16 typical regions from 26 cities of 16 provinces were collected in 2016,and their 90Sr activity concentrations were analyzed using the separation method of di (2-ethylhexyl) phosphate (HDEHP) extraction chromatography.The results revealed that the activity concentrations in 26 kinds of tea samples ranged from 0.28 to 3.78 Bq/kg,and contributed possible exposure doses of 0.44 × 10-2-6.00 × 10-2 μSv to each people.Conclusions These doses were far less than the ICRP annual dose limit of 1 mSv for the public,suggesting less impact on people's health.
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Objective To develop a rapid and reliable method for determination of 210Po using large-area grid ionization chamber α spectrometry.Methods Samples were digested using a microwave digestion system.After preparation of sample source,the concentration of 210Po in clam was detected by large-area grid ionization chamber (φ 25 cm).209Po tracer was used to obtain the recovery.Results Large-area grid ionization chamber could achieve better counting and α spectrum resolution when the optimized thickness was 250 μg/cm2.By spiking 209Po tracer in clam,the minimum detectable activity was 9.870 × 10 4 Bq and the recovery of 210Po was 98％.Conclusions Compared with the traditional method,the developed method can avoid separation process,using less quantity of sample (0.2-0.5 g dry) and simplify the measurement process.This method may be has broad application prospects.
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Objective To observe the morphological damages of hyperbilirubinemia on rat central nervous system, and evaluate the therapeutic effects of different routes of basic fibroblast growth factor (bFGF) administration. Methods Totally 90 Wistar rats were inflicted to hyperbilirubinemia models and then divided randomly into 3 groups:untreated group (BG),treated-1 group (T_ 1 G), treated-2 group (T_ 2 G), and another 30 rats served as control group (CG). bFGF injection were given at 30 min, 1, 3, 5 and 7 d by abdominal cavity (T_ 1 G,) and cranial cavity (T_ 2 G). GAP-43 expression levels and the micro-morphological features were observed with immunohistochemical assay and transmission electron microscopy respectively at 2 nd, 8 st, 28 st and 60 st day. Results ①Hyperbilirubinemia rat model was verified by gross and microscopic observation, bilirubin concentrations in the plasma and brain.②Compared to CG, the expression level of GAP-43 was significantly up-regulated in BG, T_ 1 G and T_ 2 G, especially in the later 2 groups (P
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<p><b>OBJECTIVE</b>To ascertain histology changes of hereditary gingival fibromatosis (HGF) and the location of HGF gene.</p><p><b>METHODS</b>A pedigree analyses of HGF; and the ultrastructure of gingival overgrowth tissue was observed with electron microscopy. The overgrowth of the HGF gene was defined with microsatellite markers.</p><p><b>RESULTS</b>The connective tissue of HGF consisted of coarse collagen bundles and several kinds of cells arranged abnormally, such as: epithelial cells, smooth muscle cells and so on; the HGF locus had been mapped to chromosome 5q13-q22.</p><p><b>CONCLUSIONS</b>The gingival pathologic changes resemble "hamartoma"; the findings has implications for identification of the underlying genetic basis of HGF.</p>