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Transuranics radionuclides are ubiquitous in the environment. Long term intake will cause internal radiation hazards, and it is also an important source of radioactive contamination to the environment in the future. In this paper, the source and migration behavior of transuranic radionuclides are reviewed, the existing problems in China are summarized, and the suggestions for future work are put forward.
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Objective To establish the three-dimensional (3D) finite element model of unicompartmental knee arthroplasty (UKA) with 3° and 7° posterior tibial slope at different knee flexion angles, and to study biomechanical properties and prosthetic wear of the knee joints with two types of posterior tibia slope and their effects on knee function. Methods Combining CT and MRI images of human knee joints with the 3rd-generation Oxford prosthesis, the finite element UKA model with 3° and 7° posterior tibia slope were established. The 1 kN load was applied to center point of the medial and lateral condyles of the femur to simulate the standing load of human body. The maximum stresses and distributions of the prosthesis and articular cartilage at different knee flexion angles were analyzed. ResultsThe maximum stress of the meniscus liner with 3° posterior tibia slope at 0°, 30°, 60°, 90°, 120° knee flexion angles increased by 28.06%, 68.99%, 19.45%, 21.06% and 53.38%, the distribution area was concentrated from the side of the meniscus liner to the central area, and the stress concentration was obvious at 120° knee flexion. The maximum stress of prosthesis with 3° posterior tibia slope was greater than that with 7 ° posterior tibia slope. The expansion of stress concentration area would cause wear and loosening of the prosthesis, contact stress and concentration area of the articular cartilage would subsequently increase with posterior tibia slope increasing, and stress concentration would be more obvious at high knee flexion angles. Conclusions Tibial prosthesis has the higher stress and greater wear under the condition of 3° posterior tibia slope than 7° posterior tibia slope. The research findings provide theoretical basis for the UKA design in clinic.
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Objective:To overcome the disadvantages of bismuth removal by bismuth sulfide precipitation method recommended by existing analytical standards and improve the quality of analytical result.Methods:Based on 201×7 anion exchange resin, the experimental process of bismuth removal was designed, and verified by using spiked samples and IAEA test samples.Results:Bismuth was removed by anion exchange resin. In the removal experiments of strontium, yttrium and bismuth, the chemical recovery rate of strontium and yttrium could reach (98.6 ± 0.8)% and (98.5 ± 0.7)%, respectively, with no Bi 2S 3 precipitation found. The relative standard deviation between analytical result and theoretical values was -2.97% to 5.94%, better than 3.96%-17.8% by the standard bismuth removal method. Through validation using IAEA test samples, the relative standard deviation between the reported value and the target value for 90Sr was between 3.40%-7.09%, and all the results were acceptable. Conclusions:Bismuth could be quantitatively removed using anion exchange resin without adsorption of strontium and yttrium. In addition, the bismuth removal solution system of anion exchange resin was the same as the elution system in 90Sr analysis, and the purpose of rapid bismuth removal could be achieved without conversion system. Compared with the current standard analytical method, it was feasible and better to quantitatively remove bismuth based on anion exchange resin, which could meet the needs of routine analysis of 90Sr.
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Department of Orthopedics, Yang Pu Hospital Affiliated to Tongji University,
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Objective To investigate the influence of ROI-C cervical implantation in the C5-6 segment on the C3-7 range-of-motion (ROM), biomechanical properties of the intervertebral disc and the vertebral body, and the mode of force transmission. Methods Two types of surgeries, ROI-C implantation and autograft fusion with plate fixation, were considered to establish the finite element model of cervical C5-6 segment degeneration. The ROM of C3-7 during flexion, extension, lateral bending, and axial rotation, as well as stress distributions on the adjacent discs, vertebral body, and implanted devices under two procedures, were analyzed. Results ROI-C implantation had a relatively small influence on the ROM of the adjacent segment. The stress on the vertebral discs was reduced, but the stress on the vertebral body increased significantly, with the C5 vertebral body stress increasing by 251%. In the fusion surgery model, the ROM of the surgical segment was reduced by 86%-91%, while the ROM of the adjacent segments and the stress on the vertebral disc and vertebral body increased significantly. Conclusions ROI-C implantation surgery has a relatively small influence on the cervical ROM and the intervertebral disc, and it has a greater impact on the vertebral body. The research findings provide a theoretical basis for the design of operation plans and clinical studies on ROI-C implantation and autograft fusion with plate fixation.
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Objective To establish a high throughput general multiple competitive polymerase chain reaction ( cPCR) detecting method of copy number variations ( CNVs) for the population of chromosome 1 substitution strains from wild mice.Method The selected 14 loci, including 11 CNVs on chromosome 1 and internal control loci on other three chromosmes (Chr 7, Chr 19 and Chr X), were detected based on the universal fluorescent primer multiple competitive pol-ymerase chain reaction.All specific cloned plasmids were constructed as competitors.Results Altogether 11 CNVs were designed in one panel, and the copy of Chr X accurately reflects the gender.Conclusions A rapid and high-throughput fluorescent multiplex cPCR assay is established which can be used for detection of copy number variations on chromosome 1 in mice.