Melt Electrospinning of PET and Composite PET-Aerogel Fibers: An Experimental and Modeling Study

Increasingly advanced applications of polymer fibers are driving the demand for new, high-performance fiber types. One way to produce polymer fibers is by electrospinning from polymer solutions and melts. Polymer melt electrospinning produces fibers with small diameters through solvent-free processing and has applications within different fields, ranging from textile and construction, to the biotech and pharmaceutical industries. Modeling of the electrospinning process has been mainly limited to simulations of geometry-dependent electric field distributions. The associated large change in viscosity upon fiber formation and elongation is a key issue governing the electrospinning process, apart from other environmental factors. This paper investigates the melt electrospinning of aerogel-containing fibers and proposes a logistic viscosity model approach with parametric ramping in a finite element method (FEM) simulation. The formation of melt electrospun fibers is studied with regard to the spinning temperature and the distance to the collector. The formation of PET-Aerogel composite fibers by pneumatic transport is demonstrated, and the critical parameter is found to be the temperature of the gas phase. The experimental results form the basis for the electrospinning model, which is shown to reproduce the trend for the fiber diameter, both for polymer as well as polymer-aerogel composites.     

氧化锌丁香油类根管封闭剂粘度对根管封闭性能的影响

[摘要] 目的 探讨氧化锌丁香油类根管封闭剂粘度对根管封闭性能的影响。方法 选取60颗单根管牙,随机分成6组。分别用3种不同粘度的氧化锌丁香油封闭剂和Cortisomol封闭剂各三组充填根管。经染料渗透后沿牙体长轴纵向剖开,在体视显微镜下观察根管渗漏染色长度。用扫描电镜观察根管封闭剂与根管壁的密合度。用SPSS 12.0软件作方差分析。结果 3种不同粘度的氧化锌丁香油封闭剂和Cortisomol封闭剂组组间微渗漏长度差异均有显著性,其中氧化锌丁香油封闭剂较稀组的染料渗漏长度最长,Cortisomol封闭剂较稠组的染料渗漏长度最短。结论 适当增加氧化锌丁香油类根管封闭剂的粘度可提高根管的密封程度。     

加温加湿经鼻高流量氧疗对老年脑梗死合并肺部感染患者的效果研究

目的探讨加温加湿经鼻高流量氧疗对老年脑梗死合并肺部感染患者的临床疗效。方法选取2018-01—2020-01郑州大学第二附属医院收治的60例老年脑梗死合并肺部感染患者,随机分为对照组和观察组各30例,对照组给予传统的吸氧面罩方式给氧,观察组采用加温加湿经鼻高流量氧疗,观察2组临床效果。结果治疗72 h后观察组PaO2(101.3±5.86)mmHg,PaCO2(35.96±2.55)mmHg,SaO2(93.50±4.58)%,心率(70.6±3.556)次/min,呼吸频率(18.6±1.028)次/min,均明显优于对照组的PaO2(95.12±5.11)mmHg,PaCO2(40.89±3.36)mmHg,SaO2(89.36±3.77)%,心率(83.12±1.18)次/min和呼吸频率(22.9±0.944)次/min(P<0.05)。治疗1周后观察组痰液黏稠度Ⅰ度占比70%,Ⅱ度占比30%,Ⅲ度占比0,明显低于对照组的Ⅰ度占比26.67%,Ⅱ度占比60%,Ⅲ度占比13.33%(P<0.05)。治疗72 h后观察组口鼻腔黏膜干燥者舒适度(3.29±1.07)明显优于对照组(5.99±1.23)(P<0.05),咽喉疼痛者舒适度(4.77±0.89)明显优于对照组(7.78±1.12)(P<0.05)。结论加温加湿经鼻高流量氧疗对老年脑梗死合并肺部感染患者的疗效显著,能够有效改善患者的动脉血气指标,降低心率和呼吸频率,降低痰液黏稠度,增加患者氧气吸入的舒适性和耐受性。     

碟脉灵注射液对大鼠实验性心肌梗塞的保护作用及其机制

目的：观察碟脉灵注射液（DMLI）对大鼠实验性心肌梗塞的保护作用及其机制。方法：采用大鼠结扎左冠状动脉前降支造成急性心肌梗塞模型,将动物随机分为假手术组、梗塞模型组及DMLI小、中、大剂量组,每组20只大鼠。计算急性心肌梗塞24 h后的心肌梗塞面积（MIS）,测定血清天冬酸氨基转移酶（AST）、乳酸脱氢酶（LDH）、肌酸磷酸激酶（CK）、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活性及丙二醛（MDA）含量,血浆内皮素（ET）及血管紧张素Ⅱ（AngⅡ）水平,观察全血低、中、高切变率黏度及血浆黏度变化,并测定心肌梗塞及非梗塞区游离脂肪酸（FFA）含量。结果：与梗塞模型组比较,DMLI 中、大剂量组急性心肌梗塞24 h大鼠的MIS缩小（P<0.05或P<0.01）,血清AST、LDH、CK活性及MDA降低（P<0.05或P<0.01）, SOD及GSH-Px活性升高（P<0.05或P<0.01）,血液黏度、血浆黏度、血浆ET及AngⅡ水平明显下降（P<0.05或P<0.01）,心肌梗塞及非梗塞区FFA含量降低（P<0.05或P<0.01）。结论：DMLI对大鼠实验性心肌梗塞具有明显保护作用,可能与其增强抗氧化酶活性,减少自由基对心肌的氧化损伤,纠正心肌缺血时FFA代谢紊乱,减少内源性血管活性物质ET及AngⅡ释放以及降低血液黏度等机制有关。     

麝香抗栓丸对实验性脑缺血大鼠血小板功能及血液粘度的影响

目的：观察麝香抗栓丸（SATP）对实验性脑缺血大鼠血小板功能及血液粘度的影响。方法：SATP 按1.5、3.0、6.0 g•kg^-1给大鼠连续灌胃14 d,采用结扎双侧颈总动脉伴低血压方法制造大鼠实验性脑缺血模型,15 min后测定全血及血浆粘度、血小板粘附及聚集功能及血栓弹力图等指标。结果：SATP 3.0、6.0 g•kg^-1组均能明显降低实验性脑缺血大鼠的全血粘度及血浆粘度,抑制血小板粘附和聚集功能(P<0.05～P<0.001),1.5 g•kg^-1组仅对全血低切粘度、血浆粘度及血小板5 min聚集率有明显降低作用(P<0.05),SATP 3个剂量组对大鼠血栓弹力图均无明显影响。结论：SATP可能通过降低血液粘度及抑制血小板粘附和聚集功能对大鼠实验性脑缺血产生保护作用。SATP由蜜丸改为水丸后药效明显增加。     

AA-AM-AN三元共聚物的合成及其溶液性能的研究

采用自由基水溶液共聚法制备了水溶性丙烯酸－丙烯酰胺－丙烯腈共聚物。对聚合反应温度、引发剂用量、尿素用量、聚合物浓度、电解质浓度、剪切速率、温度等因素对聚合物溶液性能的影响进行了研究。结果表明，合成的水溶性聚合物具有良好的增稠作用及耐温抗盐抗剪切等性能。     

The relationship between vascular wall shear stress and flow-mediated dilation: endothelial function assessed by phase-contrast magnetic resonance angiography

OBJECTIVES

We sought: 1) to investigate the relationship between vascular wall shear stress and flow-mediated dilation (FMD) in humans, and 2) to investigate whether this relationship could explain why FMD is greater in small arteries.

BACKGROUND

Arterial wall shear stress (WSS) is considered to be the primary stimulus for the endothelial-dependent FMD response. However, the relationship between WSS and FMD has not been investigated in humans. Furthermore, FMD is greater in small arteries, though the reasons for this phenomenon are unclear.

METHODS

Using phase-contrast magnetic resonance angiography (PMRCA), we measured hyperemic WSS and FMD in 18 healthy volunteers. Peak systolic WSS was calculated assuming a blunted parabolic velocity profile. Diameter by PCMRA and by ultrasound was compared in nine subjects.

RESULTS

Flow-mediated dilation was linearly proportional to hyperemic peak systolic WSS (r = 0.79, P = 0.0001). Flow-mediated dilation was inversely related to baseline diameter (r = 0.62, P = 0.006), but the hyperemic peak WSS stimulus was also inversely related to baseline diameter (r = 0.47, P = 0.049). Phase-contrast magnetic resonance angiography and ultrasound diameters were compared in nine subjects and correlated well (r = 0.84, p < 0.0001), but diameter by PCMRA was greater (4.1 ± 0.7 mm vs. 3.7 ± 0.5 mm, P = 0.009).

CONCLUSIONS

Arterial FMD is linearly proportional to peak hyperemic WSS in normal subjects. Thus, the endothelial response is linearly proportional to the stimulus. Furthermore, the greater FMD response in small arteries is accounted for, at least partially, by a greater hyperemic WSS stimulus in small arteries. By allowing the calculation of vascular WSS, which is the stimulus for FMD, and by imaging a fixed arterial cross-section, thus reducing operator dependence, PCMRA enhances the assessment of vascular endothelial function.     

157例子宫肌瘤患者血流变指标观察

１５７例子宫肌瘤患者血流变７项指标与健康对照组比较分析，提示 子宫肌瘤患者全血粘度、红细胞压积及血沉均较对照组有明显降低，而红细胞电泳 时间则有明显延长。     

气功对机体血液流变学的影响

对练气功者和未练气功者血液流变学的诸项指标进行了研究,发现气功组体外血栓形成湿重与红细胞聚集指数低于未练气功组(P<0.01),低切变率下的全血粘度、血栓长度和干重均比对照组显著降低(P<0.05)。认为气功能减少血栓形成、降低红细胞聚集指数和血液粘度,有助于防治心脑血管病。