目的研究呼出气一氧化氮(FeNO)、血清免疫球蛋白E(IgE)和基质金属蛋白酶9(MMP9)的水平与儿童哮喘急性发作之间的关系,为儿童哮喘的预防及治疗提供依据。方法选取沈阳市妇婴医院于2020年11月至2022年11月收治的98例支气管哮喘急性发作期...目的研究呼出气一氧化氮(FeNO)、血清免疫球蛋白E(IgE)和基质金属蛋白酶9(MMP9)的水平与儿童哮喘急性发作之间的关系,为儿童哮喘的预防及治疗提供依据。方法选取沈阳市妇婴医院于2020年11月至2022年11月收治的98例支气管哮喘急性发作期儿童作为急性组,按照病情程度分成轻度组(n=32)、中度组(n=38)和重度组(n=28),按照2∶1的比例选出49例同期在门诊治疗的处于支气管哮喘缓解期的儿童作为缓解组,随机选取健康体检儿童49例作为健康对照组,分别对他们进行FeNO、MMP9和血清IgE及肺功能[用力肺活量(FVC)、1秒用力呼气量(FEV_(1))、FEV_(1)/FVC%、最大呼气流量(PEF)]检测。应用Pearson相关分析探讨哮喘急性发作期FeNO、MMP9及血清IgE和肺功能之间的联系,并对三者在支气管哮喘急性发作中的预测价值进行分析。结果急性组、缓解组和对照组的年龄、性别、体重指数和病程的比较,差异无统计学意义(P>0.05)。急性组FeNO、MMP9、血清IgE分别为(59.95±12.65)ppb、(4.87±1.44)pg/ml、(330.63±74.88)IU/ml,缓解组分别为(25.23±8.23)ppb、(1.21±0.02)pg/ml、(152.23±32.12)IU/ml,均高于对照组的(12.43±4.09)ppb、(0.53±0.24)pg/ml、(126.34±57.33)IU/ml,差异具有统计学意义(P<0.05)。急性期和缓解期FVC、FEV1、FEV1/FVC%、PEF均低于对照组,差异具有统计学意义(P<0.05)。支气管哮喘急性发作中度组FeNO、MMP9、血清IgE水平分别为(49.23±6.23)ppb、(1.21±0.02)pg/ml、(282.61±59.83)IU/ml,重度组分别为(67.43±10.09)ppb、(0.53±0.24)pg/ml、(356.49±70.82)IU/ml,均高于轻度组的(34.62±10.65)ppb、(4.87±1.44)pg/ml,(189.21±14.33)IU/ml,差异具有统计学意义(P<0.05)。在轻度组中FeNO、MMP9和血清IgE水平均较低,而在中度组中这些指标均较高,其中FVC、FEV_(1)、FEV_(1)/FVC%和PEF均较低,差异具有统计学意义(P<0.05)。FeNO以及MMP9与血清IgE水平呈正相关(P<0.05),FeNO、MMP9以及血清IgE水平与FVC、FEV_(1)、FEV_(1)/FVC%、PEF均呈负相关(P<0.05)。MMP9在支气管哮喘的诊断中表现出了显著的优势,当达到最大约登指数时,对应的截断值为1.17,曲线下面积(Area under curve,AUC)为0.83,敏感度和特异性也分别达到了90.13%和86.5%。结论支气管哮喘急性发作的儿童血清中的FeNO、MMP9以及血清IgE水平显著增高,随肺部功能恶化程度加重而上升,可能与支气管哮喘急性发作患儿肺功能损害程度有关。展开更多
目的探讨胸腺基质淋巴细胞生成素(thymic stromal lymphopoietin,TSLP)基因rs1837253、rs3806933位点多态性与儿童哮喘易感性及Eos、IgE、FeNO水平的相关性。方法选取143例哮喘儿童作为研究组,选取同期健康体检儿童112例作为对照组。采...目的探讨胸腺基质淋巴细胞生成素(thymic stromal lymphopoietin,TSLP)基因rs1837253、rs3806933位点多态性与儿童哮喘易感性及Eos、IgE、FeNO水平的相关性。方法选取143例哮喘儿童作为研究组,选取同期健康体检儿童112例作为对照组。采用MassARRAY SNP分型技术检测2个位点基因型,散射比浊法测定血清IgE水平,分析基因型及等位基因频率在2组间的分布差异,分析不同基因型对Eos、IgE及FeNO水平的影响。结果rs1837253等位基因及基因型频率、rs3806933等位基因频率在2组间分布无统计学差异(P>0.05);哮喘组rs3806933 CT基因型频率高于对照组,CC基因型频率低于对照组(P<0.05);与野生基因型相比,携带rs1837253 CT+CC和rs3806933 CT、CT+TT基因型的儿童患哮喘风险增高(CT+CC vs TT:OR=2.737,95%CI:1.514~4.945;CT vs CC:OR=2.058,95%CI:1.194~3.543:CT+TT vs CC:OR=1.843,95%CI:1.109~3.062)。哮喘组rs1837253位点3个基因型间Eos计数总体存在统计学差异(P<0.05,多重比较后矫正P>0.05),在对照组无统计学差异(P>0.05);2位点基因型间Eos%、IgE、FeNO及rs3806933基因型间Eos计数水平无统计学差异(P>0.05)。结论TSLP基因启动子区rs1837253、rs3806933位点多态性与儿童哮喘易感性有关,rs3806933CT基因型可能作为哮喘潜在的遗传标志物,rs1837253CT+CC、rs3806933CT+TT基因型是儿童患哮喘的风险因子;rs1837253位点多态性有影响血液Eos计数的趋势;2个SNPs与Eos%、血清IgE、FeNO水平无关。展开更多
Exhaled ammonia(NH_(3))is an essential noninvasive biomarker for disease diagnosis.In this study,an acetone-modifier positive photoionization ion mobility spectrometry(AM-PIMS)method was developed for accurate qualita...Exhaled ammonia(NH_(3))is an essential noninvasive biomarker for disease diagnosis.In this study,an acetone-modifier positive photoionization ion mobility spectrometry(AM-PIMS)method was developed for accurate qualitative and quantitative analysis of exhaled NH_(3)with high selectivity and sensitivity.Acetone was introduced into the drift tube along with the drift gas as a modifier,and the characteristic NH_(3)product ion peak of(C_(3)H_(6)O)_(4)NH_(4)^(+)(K_(0)=1.45 cm^(2)/V·s)was obtained through the ion-molecule reaction with acetone reactant ions(C_(3)H_(6)O)_(2)H^(+)(K_(0)=1.87 cm^(2)/V·s),which significantly increased the peak-to-peak resolution and improved the accuracy of exhaled NH_(3)qualitative identification.Moreover,the interference of high humidity and the memory effect of NH_(3)molecules were significantly reduced via online dilution and purging sampling,thus realizing breath-by-breath measurement.As a result,a wide quantitative range of 5.87-140.92μmol/L with a response time of 40 ms was achieved,and the exhaled NH_(3)profile could be synchronized with the concentration curve of exhaled CO_(2).Finally,the analytical capacity of AM-PIMS was demonstrated by measuring the exhaled NH_(3)of healthy subjects,demonstrating its great potential for clinical disease diagnosis.展开更多
BACKGROUND Eosinophilic esophagitis(EoE)is an eosinophilic-predominant inflammation of the esophagus diagnosed by upper endoscopy and biopsies.A non-invasive and cost-effective alternative for management of EoE is bei...BACKGROUND Eosinophilic esophagitis(EoE)is an eosinophilic-predominant inflammation of the esophagus diagnosed by upper endoscopy and biopsies.A non-invasive and cost-effective alternative for management of EoE is being researched.Previous studies assessing utility of fractional exhaled nitric oxide(FeNO)in EoE were low powered.None investigated the contribution of eosinophilic inflammation of the stomach and duodenum to FeNO.AIM To assess the utility of FeNO as a non-invasive biomarker of esophageal eosinophilic inflammation for monitoring disease activity.METHODS Patients aged 6-21 years undergoing scheduled upper endoscopy with biopsy for suspected EoE were recruited in our observational study.Patients on steroids and with persistent asthma requiring daily controller medication were excluded.FeNO measurements were obtained in duplicate using a chemiluminescence nitric oxide analyzer(NIOX MINO,Aerocrine,Inc.;Stockholm,Sweden)prior to endoscopy.Based on the esophageal peak eosinophil count(PEC)/high power field on biopsy,patients were classified as EoE(PEC≥15)or control(PEC≤14).Mean FeNO levels were correlated with presence or absence of EoE,eosinophil counts on esophageal biopsy,and abnormal downstream eosinophilia in the stomach(PEC≥10)and duodenum(PEC≥20).Wilcoxon rank-sum test,Spearman correlation,and logistic regression were used for analysis.P value<0.05 was considered significant.RESULTS We recruited a total of 134 patients,of which 45 were diagnosed with EoE by histopathology.The median interquartile range FeNO level was 17 parts per billion(11-37,range:7-81)in the EoE group and 12 parts per billion(8-19,range:5-71)in the control group.After adjusting for atopic diseases,EoE patients had significantly higher FeNO levels as compared to patients without EoE(Z=3.33,P<0.001).A weak yet statistically significant positive association was found between the number of esophageal eosinophils and FeNO levels(r=0.30,P<0.005).On subgroup analysis within the EoE cohort,higher FeNO levels were noted in patients with abnormal gastric(n=23,18 vs 15)and duodenal eosinophilia(n=28,21 vs 14);however,the difference was not statistically significant.CONCLUSION After ruling out atopy as possible confounder,we found significantly higher FeNO levels in the EoE cohort than in the control group.展开更多
The lungs are the main fundamental part of the human respiratory system and are among the major organs of the human body.Lung disorders,including Coronavirus(Covid-19),are among the world’s deadliest and most life-th...The lungs are the main fundamental part of the human respiratory system and are among the major organs of the human body.Lung disorders,including Coronavirus(Covid-19),are among the world’s deadliest and most life-threatening diseases.Early and social distance-based detection and treatment can save lives as well as protect the rest of humanity.Even though X-rays or Computed Tomography(CT)scans are the imaging techniques to analyze lung-related disorders,medical practitioners still find it challenging to analyze and identify lung cancer from scanned images.unless COVID-19 reaches the lungs,it is unable to be diagnosed.through these modalities.So,the Internet of Medical Things(IoMT)and machine learning-based computer-assisted approaches have been developed and applied to automate these diagnostic procedures.This study also aims at investigating an automated approach for the detection of COVID-19 and lung disorders other than COVID-19 infection in a non-invasive manner at their early stages through the analysis of human breath.Human breath contains several volatile organic compounds,i.e.,water vapor(5.0%–6.3%),nitrogen(79%),oxygen(13.6%–16.0%),carbon dioxide(4.0%–5.3%),argon(1%),hydro-gen(1 ppm)(parts per million),carbon monoxide(1%),proteins(1%),isoprene(1%),acetone(1%),and ammonia(1%).Beyond these limits,the presence of a certain volatile organic compound(VOC)may indicate a disease.The proposed research not only aims to increase the accuracy of lung disorder detection from breath analysis but also to deploy the model in a real-time environment as a home appliance.Different sensors detect VOC;microcontrollers and machine learning models have been used to detect these lung disorders.Overall,the suggested methodology is accurate,efficient,and non-invasive.The proposed method obtained an accuracy of 93.59%,a sensitivity of 89.59%,a specificity of 94.87%,and an AUC-Value of 0.96.展开更多
Small-scale measurements of the radon exhalation rate using the flow-through and closed-loop methods were conducted on the surface of a uranium tailing pond to better understand the differences between the two methods...Small-scale measurements of the radon exhalation rate using the flow-through and closed-loop methods were conducted on the surface of a uranium tailing pond to better understand the differences between the two methods.An abnormal radon exhalation behavior was observed,leading to computational fluid dynamics(CFD)-based simulations in which dynamic radon migration in a porous medium and accumulation chamber was considered.Based on the in-situ experimental and numerical simulation results,variations in the radon exhalation rate subject to permeability,flow rate,and insertion depth were quantified and analyzed.The in-situ radon exhalation rates measured using the flow-through method were higher than those measured using the closed-loop method,which could be explained by the negative pressure difference between the inside and outside of the chamber during the measurements.The consistency of the variations in the radon exhalation rate between the experiments and simulations suggests the reliability of CFD-based techniques in obtaining the dynamic evolution of transient radon exhalation rates for diffusion and convection at the porous medium-air interface.The synergistic effects of the three factors(insertion depth,flow rate,and permeability)on the negative pressure difference and measured exhalation rate were quantified,and multivariate regression models were established,with positive correlations in most cases;the exhalation rate decreased with increasing insertion depth at a permeability of 1×10^(−11) m^(2).CFD-based simulations can provide theoretical guidance for improving the flow-through method and thus achieve accurate measurements.展开更多
Accurate measurements of the radon exhalation rate help identify and evaluate radon risk regions in the environment.Among these measurement methods,the closed-loop method is frequently used.However,traditional experim...Accurate measurements of the radon exhalation rate help identify and evaluate radon risk regions in the environment.Among these measurement methods,the closed-loop method is frequently used.However,traditional experiments are insufficient or cannot analyze the radon migration and exhalation patterns at the gas–solid interface in the accumulation chamber.The CFD-based technique was applied to predict the radon concentration distribution in a limited space,allowing radon accumulation and exhalation inside the chamber intuitively and visually.In this study,three radon exhalation rates were defined,and two structural ventilation tubes were designed for the chamber.The consistency of the simulated results with the variation in the radon exhalation rate in a previous experiment or analytical solution was verified.The effects of the vent tube structure and flow rate on the radon uniformity in the chamber;permeability,insertion depth,and flow rate on the radon exhalation rate and the effective diffusion coefficient on back-diffusion were investigated.Based on the results,increasing the inser-tion depth from 1 to 5 cm decreased the effective decay constant by 19.55%,whereas the curve-fitted radon exhalation rate decreased(lower than the initial value)as the deviation from the initial value increased by approximately 7%.Increasing the effective diffusion coefficient from 2.77×10^(-7) to 7.77×10^(-6) m^(2) s^(-1) made the deviation expand from 2.14 to 15.96%.The conclusion is that an increased insertion depth helps reduce leakage in the chamber,subject to notable back-diffusion,and that the closed-loop method is reasonably used for porous media with a low effective diffusion coefficient in view of the back-diffusion effect.The CFD-based simulation is expected to provide guidance for the optimization of the radon exhalation rate measurement method and,thus,the accurate measurement of the radon exhalation rate.展开更多
文摘目的研究呼出气一氧化氮(FeNO)、血清免疫球蛋白E(IgE)和基质金属蛋白酶9(MMP9)的水平与儿童哮喘急性发作之间的关系,为儿童哮喘的预防及治疗提供依据。方法选取沈阳市妇婴医院于2020年11月至2022年11月收治的98例支气管哮喘急性发作期儿童作为急性组,按照病情程度分成轻度组(n=32)、中度组(n=38)和重度组(n=28),按照2∶1的比例选出49例同期在门诊治疗的处于支气管哮喘缓解期的儿童作为缓解组,随机选取健康体检儿童49例作为健康对照组,分别对他们进行FeNO、MMP9和血清IgE及肺功能[用力肺活量(FVC)、1秒用力呼气量(FEV_(1))、FEV_(1)/FVC%、最大呼气流量(PEF)]检测。应用Pearson相关分析探讨哮喘急性发作期FeNO、MMP9及血清IgE和肺功能之间的联系,并对三者在支气管哮喘急性发作中的预测价值进行分析。结果急性组、缓解组和对照组的年龄、性别、体重指数和病程的比较,差异无统计学意义(P>0.05)。急性组FeNO、MMP9、血清IgE分别为(59.95±12.65)ppb、(4.87±1.44)pg/ml、(330.63±74.88)IU/ml,缓解组分别为(25.23±8.23)ppb、(1.21±0.02)pg/ml、(152.23±32.12)IU/ml,均高于对照组的(12.43±4.09)ppb、(0.53±0.24)pg/ml、(126.34±57.33)IU/ml,差异具有统计学意义(P<0.05)。急性期和缓解期FVC、FEV1、FEV1/FVC%、PEF均低于对照组,差异具有统计学意义(P<0.05)。支气管哮喘急性发作中度组FeNO、MMP9、血清IgE水平分别为(49.23±6.23)ppb、(1.21±0.02)pg/ml、(282.61±59.83)IU/ml,重度组分别为(67.43±10.09)ppb、(0.53±0.24)pg/ml、(356.49±70.82)IU/ml,均高于轻度组的(34.62±10.65)ppb、(4.87±1.44)pg/ml,(189.21±14.33)IU/ml,差异具有统计学意义(P<0.05)。在轻度组中FeNO、MMP9和血清IgE水平均较低,而在中度组中这些指标均较高,其中FVC、FEV_(1)、FEV_(1)/FVC%和PEF均较低,差异具有统计学意义(P<0.05)。FeNO以及MMP9与血清IgE水平呈正相关(P<0.05),FeNO、MMP9以及血清IgE水平与FVC、FEV_(1)、FEV_(1)/FVC%、PEF均呈负相关(P<0.05)。MMP9在支气管哮喘的诊断中表现出了显著的优势,当达到最大约登指数时,对应的截断值为1.17,曲线下面积(Area under curve,AUC)为0.83,敏感度和特异性也分别达到了90.13%和86.5%。结论支气管哮喘急性发作的儿童血清中的FeNO、MMP9以及血清IgE水平显著增高,随肺部功能恶化程度加重而上升,可能与支气管哮喘急性发作患儿肺功能损害程度有关。
文摘目的探讨胸腺基质淋巴细胞生成素(thymic stromal lymphopoietin,TSLP)基因rs1837253、rs3806933位点多态性与儿童哮喘易感性及Eos、IgE、FeNO水平的相关性。方法选取143例哮喘儿童作为研究组,选取同期健康体检儿童112例作为对照组。采用MassARRAY SNP分型技术检测2个位点基因型,散射比浊法测定血清IgE水平,分析基因型及等位基因频率在2组间的分布差异,分析不同基因型对Eos、IgE及FeNO水平的影响。结果rs1837253等位基因及基因型频率、rs3806933等位基因频率在2组间分布无统计学差异(P>0.05);哮喘组rs3806933 CT基因型频率高于对照组,CC基因型频率低于对照组(P<0.05);与野生基因型相比,携带rs1837253 CT+CC和rs3806933 CT、CT+TT基因型的儿童患哮喘风险增高(CT+CC vs TT:OR=2.737,95%CI:1.514~4.945;CT vs CC:OR=2.058,95%CI:1.194~3.543:CT+TT vs CC:OR=1.843,95%CI:1.109~3.062)。哮喘组rs1837253位点3个基因型间Eos计数总体存在统计学差异(P<0.05,多重比较后矫正P>0.05),在对照组无统计学差异(P>0.05);2位点基因型间Eos%、IgE、FeNO及rs3806933基因型间Eos计数水平无统计学差异(P>0.05)。结论TSLP基因启动子区rs1837253、rs3806933位点多态性与儿童哮喘易感性有关,rs3806933CT基因型可能作为哮喘潜在的遗传标志物,rs1837253CT+CC、rs3806933CT+TT基因型是儿童患哮喘的风险因子;rs1837253位点多态性有影响血液Eos计数的趋势;2个SNPs与Eos%、血清IgE、FeNO水平无关。
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.:22027804,21974141,and 21904125)Natural Science Foundation of Liaoning Province(Grant Nos.:2022-MS-019 and 2022-MS-016)+2 种基金Science and Technology Innovation Foundation of Dalian(Grant No.:2022JJ13SN096)Dalian Institute of Chemical Physics(Grant Nos.:DICP I202141 and DICP I202144)1+X Program for Large Cohort Study-Clinical Research Incubation Project,The Second Hospital of Dalian Medical University(Project No.:2022DXDL01).
文摘Exhaled ammonia(NH_(3))is an essential noninvasive biomarker for disease diagnosis.In this study,an acetone-modifier positive photoionization ion mobility spectrometry(AM-PIMS)method was developed for accurate qualitative and quantitative analysis of exhaled NH_(3)with high selectivity and sensitivity.Acetone was introduced into the drift tube along with the drift gas as a modifier,and the characteristic NH_(3)product ion peak of(C_(3)H_(6)O)_(4)NH_(4)^(+)(K_(0)=1.45 cm^(2)/V·s)was obtained through the ion-molecule reaction with acetone reactant ions(C_(3)H_(6)O)_(2)H^(+)(K_(0)=1.87 cm^(2)/V·s),which significantly increased the peak-to-peak resolution and improved the accuracy of exhaled NH_(3)qualitative identification.Moreover,the interference of high humidity and the memory effect of NH_(3)molecules were significantly reduced via online dilution and purging sampling,thus realizing breath-by-breath measurement.As a result,a wide quantitative range of 5.87-140.92μmol/L with a response time of 40 ms was achieved,and the exhaled NH_(3)profile could be synchronized with the concentration curve of exhaled CO_(2).Finally,the analytical capacity of AM-PIMS was demonstrated by measuring the exhaled NH_(3)of healthy subjects,demonstrating its great potential for clinical disease diagnosis.
文摘BACKGROUND Eosinophilic esophagitis(EoE)is an eosinophilic-predominant inflammation of the esophagus diagnosed by upper endoscopy and biopsies.A non-invasive and cost-effective alternative for management of EoE is being researched.Previous studies assessing utility of fractional exhaled nitric oxide(FeNO)in EoE were low powered.None investigated the contribution of eosinophilic inflammation of the stomach and duodenum to FeNO.AIM To assess the utility of FeNO as a non-invasive biomarker of esophageal eosinophilic inflammation for monitoring disease activity.METHODS Patients aged 6-21 years undergoing scheduled upper endoscopy with biopsy for suspected EoE were recruited in our observational study.Patients on steroids and with persistent asthma requiring daily controller medication were excluded.FeNO measurements were obtained in duplicate using a chemiluminescence nitric oxide analyzer(NIOX MINO,Aerocrine,Inc.;Stockholm,Sweden)prior to endoscopy.Based on the esophageal peak eosinophil count(PEC)/high power field on biopsy,patients were classified as EoE(PEC≥15)or control(PEC≤14).Mean FeNO levels were correlated with presence or absence of EoE,eosinophil counts on esophageal biopsy,and abnormal downstream eosinophilia in the stomach(PEC≥10)and duodenum(PEC≥20).Wilcoxon rank-sum test,Spearman correlation,and logistic regression were used for analysis.P value<0.05 was considered significant.RESULTS We recruited a total of 134 patients,of which 45 were diagnosed with EoE by histopathology.The median interquartile range FeNO level was 17 parts per billion(11-37,range:7-81)in the EoE group and 12 parts per billion(8-19,range:5-71)in the control group.After adjusting for atopic diseases,EoE patients had significantly higher FeNO levels as compared to patients without EoE(Z=3.33,P<0.001).A weak yet statistically significant positive association was found between the number of esophageal eosinophils and FeNO levels(r=0.30,P<0.005).On subgroup analysis within the EoE cohort,higher FeNO levels were noted in patients with abnormal gastric(n=23,18 vs 15)and duodenal eosinophilia(n=28,21 vs 14);however,the difference was not statistically significant.CONCLUSION After ruling out atopy as possible confounder,we found significantly higher FeNO levels in the EoE cohort than in the control group.
文摘The lungs are the main fundamental part of the human respiratory system and are among the major organs of the human body.Lung disorders,including Coronavirus(Covid-19),are among the world’s deadliest and most life-threatening diseases.Early and social distance-based detection and treatment can save lives as well as protect the rest of humanity.Even though X-rays or Computed Tomography(CT)scans are the imaging techniques to analyze lung-related disorders,medical practitioners still find it challenging to analyze and identify lung cancer from scanned images.unless COVID-19 reaches the lungs,it is unable to be diagnosed.through these modalities.So,the Internet of Medical Things(IoMT)and machine learning-based computer-assisted approaches have been developed and applied to automate these diagnostic procedures.This study also aims at investigating an automated approach for the detection of COVID-19 and lung disorders other than COVID-19 infection in a non-invasive manner at their early stages through the analysis of human breath.Human breath contains several volatile organic compounds,i.e.,water vapor(5.0%–6.3%),nitrogen(79%),oxygen(13.6%–16.0%),carbon dioxide(4.0%–5.3%),argon(1%),hydro-gen(1 ppm)(parts per million),carbon monoxide(1%),proteins(1%),isoprene(1%),acetone(1%),and ammonia(1%).Beyond these limits,the presence of a certain volatile organic compound(VOC)may indicate a disease.The proposed research not only aims to increase the accuracy of lung disorder detection from breath analysis but also to deploy the model in a real-time environment as a home appliance.Different sensors detect VOC;microcontrollers and machine learning models have been used to detect these lung disorders.Overall,the suggested methodology is accurate,efficient,and non-invasive.The proposed method obtained an accuracy of 93.59%,a sensitivity of 89.59%,a specificity of 94.87%,and an AUC-Value of 0.96.
基金National Natural Science Foundation of China(No.11575080)Hunan Provincial Natural Science Foundation of China(No.2022JJ30482)Hunan Provincial Innovation Foundation for Postgraduate(No.QL20220206).
文摘Small-scale measurements of the radon exhalation rate using the flow-through and closed-loop methods were conducted on the surface of a uranium tailing pond to better understand the differences between the two methods.An abnormal radon exhalation behavior was observed,leading to computational fluid dynamics(CFD)-based simulations in which dynamic radon migration in a porous medium and accumulation chamber was considered.Based on the in-situ experimental and numerical simulation results,variations in the radon exhalation rate subject to permeability,flow rate,and insertion depth were quantified and analyzed.The in-situ radon exhalation rates measured using the flow-through method were higher than those measured using the closed-loop method,which could be explained by the negative pressure difference between the inside and outside of the chamber during the measurements.The consistency of the variations in the radon exhalation rate between the experiments and simulations suggests the reliability of CFD-based techniques in obtaining the dynamic evolution of transient radon exhalation rates for diffusion and convection at the porous medium-air interface.The synergistic effects of the three factors(insertion depth,flow rate,and permeability)on the negative pressure difference and measured exhalation rate were quantified,and multivariate regression models were established,with positive correlations in most cases;the exhalation rate decreased with increasing insertion depth at a permeability of 1×10^(−11) m^(2).CFD-based simulations can provide theoretical guidance for improving the flow-through method and thus achieve accurate measurements.
基金This work was supported by the National Natural Science Foundation of China(No.11575080)the National Natural Science Foundation of Hunan Province,China(No.2022JJ30482)the Hunan Provincial Innovation Foundation for Postgraduates(No.QL20220206).
文摘Accurate measurements of the radon exhalation rate help identify and evaluate radon risk regions in the environment.Among these measurement methods,the closed-loop method is frequently used.However,traditional experiments are insufficient or cannot analyze the radon migration and exhalation patterns at the gas–solid interface in the accumulation chamber.The CFD-based technique was applied to predict the radon concentration distribution in a limited space,allowing radon accumulation and exhalation inside the chamber intuitively and visually.In this study,three radon exhalation rates were defined,and two structural ventilation tubes were designed for the chamber.The consistency of the simulated results with the variation in the radon exhalation rate in a previous experiment or analytical solution was verified.The effects of the vent tube structure and flow rate on the radon uniformity in the chamber;permeability,insertion depth,and flow rate on the radon exhalation rate and the effective diffusion coefficient on back-diffusion were investigated.Based on the results,increasing the inser-tion depth from 1 to 5 cm decreased the effective decay constant by 19.55%,whereas the curve-fitted radon exhalation rate decreased(lower than the initial value)as the deviation from the initial value increased by approximately 7%.Increasing the effective diffusion coefficient from 2.77×10^(-7) to 7.77×10^(-6) m^(2) s^(-1) made the deviation expand from 2.14 to 15.96%.The conclusion is that an increased insertion depth helps reduce leakage in the chamber,subject to notable back-diffusion,and that the closed-loop method is reasonably used for porous media with a low effective diffusion coefficient in view of the back-diffusion effect.The CFD-based simulation is expected to provide guidance for the optimization of the radon exhalation rate measurement method and,thus,the accurate measurement of the radon exhalation rate.
