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Objective To test the validity for mechanical equation of the TC4 self-tapping bone screw and analyze the influence of bone screw parameters on its mechanical properties. Methods In order to derive the equation of self-tapping and pull-out for bone screw, the physical model of bone screw-polyurethane foam block was built. By reference of ASTMF543-07 standard specification and test method for metallic medical bone screw, the mechanical verification tests of selected conical head shallow thread locking bone screw (HAZ) and conical head deep thread locking bone screw (HBZ) with different diameters were performed on Instron E3000 mechanical testing machine, and the data of self-tapping force, self-tapping torque and pull-out force from 5 groups of bone screws were tested respectively. Results The calculated and measured values were basically the same, except for a few points with large individual errors. The average error of the two values was 11.02%, so the theoretical calculation formula was highly credible. The bone screw with a larger diameter or a higher tooth height would require greater self-tapping force and pull-out force. Conclusions The research results provide the calculation basis for mechanical properties of bone screw and the research direction for optimization and improvement of bone screw in future.
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Objective To analyze factors that affect axial mechanical performance of the posterior pedicle fixation system. Methods The mechanical model for axial mechanical properties of the posterior pedicle fixation system was established to perform mechanical analysis. By referring to the Standard YY/T 0961-2014, tests on axial ejection force and axial clamping torque of JHL-I multi-axis components, JHL-I single-axis components, JHL-V multi-axis components and JHL-V single-axis components were performed by using Instron E3000 and Instron E10000 mechanical testing machines. Results The ejection rigidity of the single-axis component of vertebral nail system was significantly higher than that of the multi-axis component of vertebral nail system; the torsion rigidity of JHL-V was higher than that of JHL-I. The type and size of the locking bolt as well as its locking torque were the main factors affecting axial ejection force of the posterior spinal pedicle fixation system; the size of the locking bolt and the diameter of the connection rod were the main factors affecting axial clamping torque of the system; axial mechanical properties of the system could be improved by increasing the diameter of the connecting rod, the coefficient of friction between each connecting element, and the pitch diameter of the locking bolt. Conclusions The research findings provide references for optimizing and improving axial mechanical properties of the posterior pedicle fixation system.
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Objective To understand the impact of meteorological and environmental conditions on the spread of COVID-19, and to provide a scientific basis for prediction, prevention and control of COVID-19. Methods The number of confirmed cases, population density and meteorological data of all cities in Hubei Province during COVID-19 outbreak period were collected. The relationship between COVID-19 infection rate and climatic factors were analyzed using Excel and SPSS software. Results The infection rate of COVID-19 had the greatest correlation with population density. The infection rate of COVID-19 showed a very significant power-law relationship with the number of the hot days before COVID-19 outbreak, and it also had a good correlation with the high temperature accumulation, the rank of hot days and the drought intensity. Conclusion The adverse effect of high temperature and heat wave on the human body had an impact on the spread of COVID-19. The ability of people in different areas to resist high temperature was different because of different climates. Drought may affect the spread of COVID-19 by destroying the ecological environment.
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Objective:To analyze the prognostic factors for survival in elderly patients with glioma.Methods:We performed a retrospective analysis of prognostic factors for elderly patients with glioma,who were treated by the same attending doctor during June 2014 and June 2016,to investigate the correlations of the age,dimension of pathology,histological grade,extent of resection,adjuvant therapy,preoperative Karnofsky Performance Scale (KPS) score,postoperative KPS score,molecular markers [isocitrate dehydrogenase-1 (IDHH-1),O6-methylguanine DNA-transferase (MGMT),epidermal growth factor receptor (EGFR),Ki-67] with the prognosis.Results:A total of 45 patients were included in the study.The median overall survival (OS) was 11 months.The median progression-free survival (PFS) was 6 months.Univariate analysis revealed that the age,gender,dimension ofpathology,histological grade and preoperative KPS score had no significant correlation with survival (P＞0.05).The gross total resection,higher postoperative KPS score,adjuvant therapy,lower Ki-67 index were significantly correlated with survival.The expressions of MGMT and EGFR were significant factors for survival.High postoperative KPS score (P=0.019),adjuvant therapy (P=0.024),and the expression of MGMT (P=0.026) were independent predictors for increased median OS in a multivariate regression model.Conclusion:The extent of resection,adjuvant therapy,postoperative KPS score and molecular markers are the influential factors for survival.Larger prospective studies are needed to confirm these findings.
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Objective To investigate the pathogens distribution in neonatal blood culture and their drug resistance to antibacteri‐al drugs in Dalian City .Methods The routine blood culture ,identification and drug sensitivity test were carried out in the hospital‐ized neonates from August 2014 to August 2015 .And the obtained data were analyzed .Results A total of 186 strains of pathogenic bacteria were detected from 1 570 cases of neonatal blood culture and the positive rate was 11 .8% .Gram positive bacteria accounted for 74 .2% (138/186) and were dominated by Staphylococcus epidermidis .Gram negative bacteria accounted for 25 .3% (47/186) , which were mainly onion burkholderia bacterium .One strain was fungus ,accounting for 0 .5% .The drug sensitivity test results showed that Gram positive bacteria had the higher resistance rate to penicillin and erythromycin (80 .0% -90 .0% ) ,100 .0% sensi‐tivity to vancomycin ,linezolid and teicoplanin ;E .coli and K .pneumoniae had the highest resistance rate to ampicillin (88 .2% -100 .0% ) ,100 .0% sensitivity to imipenem ,amikacin ,low resistance rate to piperacillin/tazobactam ,cefoperazone/sulbactam ,amoxi‐cillin/clavulanic acid ,cefepime and ceftazidime (0% -10 .0% ) .The resistance rate of onion burkholderia bacterium to ticarcillin/clavulanate and meropenem was higher than 80 .0% ,which had 100 .0% sensitivity to cefoperazone /sulbactam ,levofloxacin ,mino‐cycline and compound sulfamethoxazole .Conclusion The neonatal blood culture pathogen in Dalian City is dominated by Gram pos‐itive bacteria ,coagulase negative staphylococcus is the main pathogen .Due to the different regional environmental ,pathogens and drug resistance should be regularly monitored and analyzed to provide objective and accurate basis for clinical rational use of anti‐bacterial drugs .
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Objective To investigate the effects of surface anesthesia on assisted balloon dilatation when treating dysphagia caused by radiotherapy for nasopharyngeal carcinoma.Methods Fifty-four patients with dysphagia after radiotherapy were divided randomly into an anesthesia group and a non-anesthesia group.The anesthesia group received anesthetics before treatment while the non-anesthesia group did not.All of the patients were treated with low-frequency electrical stimulation and assisted balloon dilatation for 3 weeks.They were then assessed using videofluoroscopy and self-reports of difficulty in swallowing before and after the treatment.Results After the treatment, significant improvement was observed in pharyngeal delay time, in cricopharyngeal opening, and in laryngeal elevation and forwardness.There was also a significant decrease in self-reported swallowing difficulty and failed swallows in both groups compared with before the treatment.The improvements in the non-anesthesia group were significantly greater than in the anesthesia group.After the treatment, the average aspiration rate of the anesthesia group was significantly higher than before treatment and higher than that of the non-anesthesia group.The improvement in oral intake of the non-anesthesia group was significantly better than that of the anesthesia group.Conclusion Balloon dilatation and low-frequency electrical stimulation have a synergistic effect and can improve patients' swallowing after radiation-induced cranial nerve damage, thus promoting survival.Assisted balloon dilatation without anesthesia has a better effect than when surface anesthesia is used.
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18F fluorodeoxyglucose, as a kind of tracer, has its limitations in positron emission tomography/computed tomography (PET/CT). 18F-fluorothymidine (18F-FLT) is a kind of new tracer. The value of 18F-FLT in diagnosis of tumor, tumor staging and assessment of therapeutic effects was reviewed in this article.
