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Objective@#To understand the occupational hazard and distribution of silica dust (free SiO2≥10%) in the workplace environment of the enterprises in Fengxian District, and to provide scientific basis for improving the working environment and protecting the physical and mental health of the workers.@*Methods@#Individual sampling monitoring and on-site labor hygiene investigation were conducted on 421 workers involved in 87 silicon dust enterprises in the jurisdiction from 2014 to 2018, and measured concentration-time weighted average (CTWA) .@*Results@#The results showed that the range of the CTWA was (0.021~17.000) mg/m3, the median was 1.600 mg/m3, and the qualified rate of 30.88%. The difference of total dust concentration was statistically significant in different years (Z=38.831, P<0.05) . The qualified rate of small-scale enterprises is higher than that of medium-scale enterprises (χ2=9.472, P<0.05) . The qualified rate of other domestic enterprises is higher than that of private enterprises and foreign enterprises (χ2=10.089, P<0.05) . The acceptance rate of metal products manufacturing is lower than that of general equipment manufacturing and other manufacturing enterprises (χ2=64.626, P<0.05) . The qualification rate of natural ventilation is higher than that of mechanical ventilation (χ2=6.278, P<0.05) .@*Conclusion@#The enterprises involved in silicon production in Fengxian District need to further strengthen the production process reform and improve the ventilation and dust removal protection measures. Widely carry out the publicity of occupational disease prevention and control law, conduct targeted pre-job training, improve workers' awareness of self-protection, and protect the occupational health of workers in many ways.
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BACKGROUND: Hydroxyapatite/β-tricalcium phosphate biphasic ceramic bone has good cel compatibility, but its mechanical properties are poor. OBJECTIVE: To construct chitosan/ or calcium alginate/biphasic ceramic bone scaffolds and to detect their mechanical properties and cytocompatibility. METHODS: Different concentrations of chitosan (2%, 4%, 7%, 10%) or calcium alginate (3%, 4%, 5%, 7%) were mixed with biphasic ceramic bone to prepare chitosan/biphasic ceramic bone scaffold and calcium alginate/biphasic ceramic bone scaffold. Their morphology and structure, coagulation time, anti-dissolution properties, shear force, compressive strength and cel compatibility were detected. RESULTS AND CONCLUSION: (1) Coagulation time: with the concentration increase, the initial and final setting time of these two kinds of composite scaffolds were prolonged to some extent. (2) Scanning electron microscopy: these two kinds of composite scaffolds showed porous microstructures with different pore sizes. (3) Anti-dissolution properties: the calcium alginate/biphasic ceramic bone scaffold (3%, 4%, 5%, 7%) and chitosan/biphasic ceramic bone scaffold (7%, 10%) had good anti-dissolution properties in the liquid. (4) Mechanical strength: with the concentration increase, the shear force and compressive strength of the calcium alginate/biphasic ceramic bone scaffold were reduced. (5) Cel compatibility: the cytotoxicity of chitosan/ or calcium alginate/biphasic ceramic bone scaffolds was graded as 0-1 or 2-3, respectively. These results show that the chitosan/biphasic ceramic bone scaffold has better mechanical properties and cel compatibility than the calcium alginate/biphasic ceramic bone scaffold.
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BACKGROUND: The conical telescopic crown denture has a better long-term effect on dentition defects of few remaining teeth than the traditional removable denture. However, there are few studies to analyze the application of these two kinds of repair methods using the finite element method. OBJECTIVE: To compare the stress distribution of the isolated abutment tooth repaired using the conical telescopic crown denture and traditional removable denture. METHODS: Two-dimensional images of the mandible and dentition in healthy adults were scanned by CT. Three-dimensional finite element models of conical telescopic crown denture and traditional removable denture were established in the mandible only with the bilateral canines. Under the same vertical and oblique loadings, the maximum equivalent stress of the abutment, periodontal membrane or edentulous alveolar ridge was compared between two repair methods. RESULTS AND CONCLUSION: Under the vertical and oblique loadings, the total stress of abutment and periodontal membrane in the traditional removable denture was higher than that in the conical telescopic crown denture and the stress in the corresponding ring was concentrated obviously; the total stress of edentulous alveolar ridge in the conical telescopic crown denture was slightly larger than that in the traditional removable denture, but the stress was wel -distributed and concentrated in a smal area. Under the oblique loading, the total stress of abutment, periodontal membrane and edentulous alveolar ridge was higher than that under the vertical loading in these two dentures, and the stress was concentrated in the periodontal membrane of lingual neck, but the total stress in the traditional removable denture was larger, with a wider concentration range. These findings indicate that the stress on the supporting tissue of conical telescopic crown denture is more evenly distributed within a smal er range than that of traditional removable denture, and the former is more fit for the health of abutment, periodontal tissues and edentulous alveolar ridge.
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Objective To study the efficacy and safety of implantation of a modified temporary self-expanding metallic stent for cardia achalasia.Methods A total of 30 patients diagnosed as having cardia achalasia were randomly divided into 2 groups,group A (traditional stents) and group B (modified stents)(n =15 in each group).Two days after stent implantation at the cardia by endoscopy,stents were withdrawn with endoscope guided by X-ray.LES Pressure,X-ray images ( including the diameter of the most dilated part of esophageal and the most narrow part of cardia) and the symptoms of dysphagia were compared before and half year after the treatment.The width changes of the most narrow stenting part on the point of stenting and 2 days after removal were compared.The side effects and complications during the treatment were recorded.Results All thirty stents were successfully implanted and removed.Stent dislocation occured in 2 cases in group A,but none in group B.Dysphagia had significant improvement after the treatment in both groups ( P ＜ 0.05 ),but the recurrence rate of group A ( 26.7％ ) was significantly higher than group B (6.67％ ) in 6 months ( P ＜ 0.05 ).LES pressure and X-ray images of both groups significantly improved after treatment ( P ＜ 0.001 ),and those of group B were superior to group A ( P ＜ 0.05 ).There was no difference in adverse reaction between the two groups.No perforation occured in any group.Conclusion Self-expanding metallic stents is safe for patients with cardia achalasia,with implantation convenience,symptomatic improvement,low recurrence,and few complications or dislocation.
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<p><b>OBJECTIVE</b>To explore the variety of the genetic polymorphism of eight Prunella germplasm resources by AFLP analysis.</p><p><b>METHOD</b>The amplified fragment length polymorphism (AFLP) tags were applied to screen out 32 selective amplification primer pairs, the amplified bands as original matrix were analyzed with NTSYS-PC software for the similarity between the Prunella germplasm and the construction of genetic phylogenetic tree.</p><p><b>RESULT</b>SDS extraction of genomic Prunella DNA showed a good quality, could meet the requirements of AFLP analysis. From 32 selective amplification primer pairs, 10 pairs with strong polymorphism, better band and higher resolution were used for the construction of the AFLP Prunella fingerprint, all eight Prunella germplasms were separated, they were divided into 3 categories.</p><p><b>CONCLUSION</b>Prunella germplasm resources are rich in genetic diversity, certain morphological characteristics and differences are associate with genotype.</p>