ABSTRACT
Spinning fibers from carbon nanotube (CNT)/superacid dispersions has emerged as a promising strategy for industrial-scale production of high-performance CNT fibers (CNTFs). The oxygen content and types of functional groups on CNT surfaces significantly influence dispersion, assembly processes, and fiber properties. In this study, Tuball-SWCNTs were purified and oxidized at varying levels. The dispersion behavior of CNTs with different oxidation levels in chlorosulfonic acid was systematically observed, and the mechanical properties of fibers spun from these dispersions were compared. By adjusting the dispersion concentration, highly oriented CNTFs were produced with a specific strength of 1.03 N/tex, a tensile strength of 1.59 GPa, and an electrical conductivity of 3.58 MS/m. Further investigations indicated that oxygen-containing functional groups decrease the coagulation rate, increasing the maximum draw ratio during spinning and improving CNT alignment in the fibers. Molecular dynamics simulations demonstrated that these functional groups (-OH, -COOH) enhance load transfer between CNTs through hydrogen bonding. This specific strength is the highest achieved using Tuball-SWCNTs for superacid-spun fibers, surpassing previous works due to the oxidation-controlled coagulation rate, enhanced fiber orientation, and improved load transfer via hydrogen bonding. This study provides insights for designing and optimizing high-performance CNTFs.
ABSTRACT
To observe the effect of Xiaoqinglong decoction combined with noninvasive ventilation on procalcitonin (PCT), blood gas analysis and respiratory functions in acute exacerbation of chronic obstructive pulmonary disease in the elderly (AECOPD), and investigate its correlation and clinical significance. Eighty-four elderly AECOPD patients with respiratory failure in our hospital from January 2015 to October 2017, were randomly divided into control group and observation group, 42 cases in each group. The control group received western medicine combined with noninvasive ventilator therapy, and the patients in observation group additionally received Xiaoqinglong decoction on the basis of the treatment in control group. Both groups were treated for 2 weeks. The clinical effects of two groups were observed and their PCT, blood gas analysis outcomes [arterial oxygen partial pressure (PaO2), arterial partial pressure of carbon dioxide (PaCO2), respiratory function, forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/FVC], TCM syndrome score and other indexes and adverse reactions were compared before and after treatment. The total efficiency was 95.24% (40/42) in observation group, higher than 76.19% (32/42) in control group, with statistically significant difference (P<0.05). There were no statistically significant differences in PCT, PaO2, PaCO2, FVC, FEV1/FVC, FEV1, and TCM syndrome scores between two groups before treatment. But after treatment, PCT and PaCO2 levels in the observation group were lower and PaO2, FVC, FEV1/FVC, FEV1 levels was higher than those in the control group (P<0.05); TCM syndrome scores were lower than those in the control group (P<0.05); both groups had no obvious adverse reactions. The results showed that Xiaoqinglong decoction combined with noninvasive ventilator could significantly reduce the procalcitonin level, effectively improve the respiratory function and blood gas analysis indexes, and significantly reduce the clinical symptoms in AECOPD patients, so it is worthy of promotion.
