目的:探讨颌骨单纯性骨囊肿(simple bone cyst,SBC)的临床诊断要点。方法:选择南昌大学附属口腔医院口腔颌面外科2010—2020年间收治的63例SBC及100例颌骨囊肿患者作为研究对象,收集2组患者的临床、影像学及手术资料,采用筛检试验评价...目的:探讨颌骨单纯性骨囊肿(simple bone cyst,SBC)的临床诊断要点。方法:选择南昌大学附属口腔医院口腔颌面外科2010—2020年间收治的63例SBC及100例颌骨囊肿患者作为研究对象,收集2组患者的临床、影像学及手术资料,采用筛检试验评价的方法探讨SBC的临床诊断要点,从而为该疾病的临床诊断及治疗方式的选择提供依据。结果:本研究共纳入63例SBC患者,其平均诊断年龄为20岁(7~79岁)。其中,上颌骨2例,下颌骨61例。采用串联实验进行筛检变量组合,结果显示,x1(年龄分组)和x3(体格检查有无阳性体征)组合的受试者工作特征曲线下面积(area under the curve,AUC)为0.831,灵敏度为68.18%,特异度为98.10%,约登指数为0.6628;x2(部位:上/下)和x3组合的AUC为0.865,灵敏度为86.36%,特异度为86.67%,约登指数为0.7303;x1、x3、x5(骨质是否膨隆、吸收)组合的AUC为0.776,灵敏度为56.06%,特异度为99.05%,约登指数为0.5511。结论:年龄小于20岁、体格检查无阳性体征、影像学表现为边界清楚的单房型囊性透射影,且颌骨无明显骨质膨隆的患者可以初步诊断为SBC。展开更多
This study aims to analyze the influence of the polycyclic aromatic hydrocarbon(PAH)content in diesel on the physical and chemical properties of diesel soot particles.Four diesel fuels with different PAH content were ...This study aims to analyze the influence of the polycyclic aromatic hydrocarbon(PAH)content in diesel on the physical and chemical properties of diesel soot particles.Four diesel fuels with different PAH content were tested on a 11.6 L direct-injection diesel engine.The raw particulate matter(PM)before the after-treatment devices was collected using the thermophoresis sampling system and the filter sampling system.A transmission electron microscope and Raman spectrometer are used to analyze the physical properties of the soot particles,including morphology,primary particle size distribution,and graphitization degree.A Fourier transform infrared spectrometer and thermogravimetric analyzer are used to characterize the surface chemical composition and oxidation reactivity of soot particles,respectively.The results show that as the PAH content in the fuel decreases,the size of the primary soot particles decreases from 29.58 to 26.70 nm.The graphitization degree of soot particles first increases and then decreases,and the relative content of the aliphatic hydrocarbon functional groups of soot particles first decreases and then increases.The T_(10),T_(50),and T_(90) of soot from high-PAH fuel are 505.3,589.3,and 623.5℃,while those from low-PAH fuel are 480.1,557.5,and 599.2℃,respectively.This indicates that exhaust PM generated by the low-PAH fuel has poor oxidation reactivity.However,as the PAH content in fuel is further decreased,the excessively high cetane number may cause uneven mixing and incomplete combustion,leading to enhanced oxidation reactivity.展开更多
以某重型柴油机的连杆轴承为研究对象,通过仿真计算发现Singhal、Schnerr and Sauer及Zwart-Gerber-Belamri这3种空化模型中,Singhal模型对峰值压力更敏感,用该空化模型探究了进油口位置对空化范围的影响及轴颈和轴瓦之间径向相对运动...以某重型柴油机的连杆轴承为研究对象,通过仿真计算发现Singhal、Schnerr and Sauer及Zwart-Gerber-Belamri这3种空化模型中,Singhal模型对峰值压力更敏感,用该空化模型探究了进油口位置对空化范围的影响及轴颈和轴瓦之间径向相对运动对油膜空化的影响。结果表明:对于稳态计算模型,沿着轴颈转动方向,最小油膜厚度下游侧出现显著的空化现象,且空化范围受到最小油膜厚度和进油口之间范围的影响;而在动态仿真过程中,当轴间隙减小时,峰值压力逐步增加,在最小轴间隙(1μm)处达到最大(187 MPa);当轴间隙增大时,峰值压力突降,此时在最小油膜厚度下游处将发生显著空化;空化主要发生和消失的过程均发生在轴颈远离轴瓦的过程中,其中当轴间隙约为40μm时空化最为剧烈;随着轴间隙进一步增加,空化程度逐渐减弱,在轴间隙约为110μm时空化消失。展开更多
文摘目的:探讨颌骨单纯性骨囊肿(simple bone cyst,SBC)的临床诊断要点。方法:选择南昌大学附属口腔医院口腔颌面外科2010—2020年间收治的63例SBC及100例颌骨囊肿患者作为研究对象,收集2组患者的临床、影像学及手术资料,采用筛检试验评价的方法探讨SBC的临床诊断要点,从而为该疾病的临床诊断及治疗方式的选择提供依据。结果:本研究共纳入63例SBC患者,其平均诊断年龄为20岁(7~79岁)。其中,上颌骨2例,下颌骨61例。采用串联实验进行筛检变量组合,结果显示,x1(年龄分组)和x3(体格检查有无阳性体征)组合的受试者工作特征曲线下面积(area under the curve,AUC)为0.831,灵敏度为68.18%,特异度为98.10%,约登指数为0.6628;x2(部位:上/下)和x3组合的AUC为0.865,灵敏度为86.36%,特异度为86.67%,约登指数为0.7303;x1、x3、x5(骨质是否膨隆、吸收)组合的AUC为0.776,灵敏度为56.06%,特异度为99.05%,约登指数为0.5511。结论:年龄小于20岁、体格检查无阳性体征、影像学表现为边界清楚的单房型囊性透射影,且颌骨无明显骨质膨隆的患者可以初步诊断为SBC。
基金National Key Research and Development Program of China(2017YFB0306605)Key Laboratory of Engines at Tianjin University(Grant No.K2022-06).
文摘This study aims to analyze the influence of the polycyclic aromatic hydrocarbon(PAH)content in diesel on the physical and chemical properties of diesel soot particles.Four diesel fuels with different PAH content were tested on a 11.6 L direct-injection diesel engine.The raw particulate matter(PM)before the after-treatment devices was collected using the thermophoresis sampling system and the filter sampling system.A transmission electron microscope and Raman spectrometer are used to analyze the physical properties of the soot particles,including morphology,primary particle size distribution,and graphitization degree.A Fourier transform infrared spectrometer and thermogravimetric analyzer are used to characterize the surface chemical composition and oxidation reactivity of soot particles,respectively.The results show that as the PAH content in the fuel decreases,the size of the primary soot particles decreases from 29.58 to 26.70 nm.The graphitization degree of soot particles first increases and then decreases,and the relative content of the aliphatic hydrocarbon functional groups of soot particles first decreases and then increases.The T_(10),T_(50),and T_(90) of soot from high-PAH fuel are 505.3,589.3,and 623.5℃,while those from low-PAH fuel are 480.1,557.5,and 599.2℃,respectively.This indicates that exhaust PM generated by the low-PAH fuel has poor oxidation reactivity.However,as the PAH content in fuel is further decreased,the excessively high cetane number may cause uneven mixing and incomplete combustion,leading to enhanced oxidation reactivity.
文摘以某重型柴油机的连杆轴承为研究对象,通过仿真计算发现Singhal、Schnerr and Sauer及Zwart-Gerber-Belamri这3种空化模型中,Singhal模型对峰值压力更敏感,用该空化模型探究了进油口位置对空化范围的影响及轴颈和轴瓦之间径向相对运动对油膜空化的影响。结果表明:对于稳态计算模型,沿着轴颈转动方向,最小油膜厚度下游侧出现显著的空化现象,且空化范围受到最小油膜厚度和进油口之间范围的影响;而在动态仿真过程中,当轴间隙减小时,峰值压力逐步增加,在最小轴间隙(1μm)处达到最大(187 MPa);当轴间隙增大时,峰值压力突降,此时在最小油膜厚度下游处将发生显著空化;空化主要发生和消失的过程均发生在轴颈远离轴瓦的过程中,其中当轴间隙约为40μm时空化最为剧烈;随着轴间隙进一步增加,空化程度逐渐减弱,在轴间隙约为110μm时空化消失。
