2 research outputs found
Thermal-Oxidation-Resistant Poly(Carborane-Silane) for Protective Coatings Under Harsh Environments
Thermal-oxidation-resistant
polymers are critical for
devices/components
used under harsh environments where high temperature and an oxidative
atmosphere lead to degradation and failure of polymeric parts. Herein,
vinyl-containing poly(carborane-silane) (VCP) with good thermal-oxidative
stability has been prepared through vinyl-modified m-carborane and silane. The cured VCP (c-VCP) could resist high temperature
in both inert and oxidative atmospheres. In comparison to traditional
carborane-siloxane copolymers, c-VCP aimed at lowering the oxygen
content and simultaneously increasing the boron content, allowing
maximum ability to capture oxygen atoms. In an oxidative atmosphere,
the formation of the boron oxide layer brought nearly 45% weight gain
rather than a weight decrease, which protected the matrix from thermal-oxidative
degradation. The mechanism of thermal-oxidative degradation was also
investigated based on Flynn–Wall–Ozawa method. The boron
oxide layer increased the degradation activation energy (Ea) and hindered direct contact of inner materials with
oxygen atoms. When the carbon fibers were coated with c-VCP, the char
yield could be increased from 0 to 57 wt % at 1000 °C in air,
which demonstrated that c-VCP coating could effectively protect carbon
fiber from oxidation at high temperature in air, also indicating potential
applications as anti-thermal-oxidative materials for harsh environments
Table_1_Validity of the SARC-F questionnaire in assessing sarcopenia in patients with chronic kidney disease: a cross-sectional study.DOCX
ObjectiveTo examine the validity of the 5-component SARC-F questionnaire for screening sarcopenia among patients with chronic kidney disease (CKD).MethodsEligible participants were enrolled from the Department of Nephrology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine from March 2019 to November 2019. Evaluations were performed using the self-administered SARC-F questionnaire. Sarcopenia was diagnosed by grip strength, the chair stand test and appendicular skeletal muscle mass. The severity of sarcopenia was evaluated by gait speed. We calculated the sensitivity and specificity of the SARC-F to evaluate construct validity. Moreover, receiver operating characteristic (ROC) curve analysis was performed to identify the cutoff value for nondialysis-dependent (NDD) CKD patients’ and maintenance hemodialysis (MHD) patients’ scores.ResultsA total of 105 NDD-CKD patients and 125 MHD patients were included, and the prevalence of sarcopenia was 5.7 and 31.2%, respectively. Among them, there were 21 (16.8%) MHD patients with severe sarcopenia but no NDD-CKD patients with severe sarcopenia. The sensitivity and specificity of the SARC-F were 16.7 and 98.0% for NDD-CKD patients, and 48.7 and 89.5% for MHD patients, respectively. For NDD-CKD patients, the area under the receiver operating characteristic curve (AUROC) of the total SARC-F score was 0.978 (95% confidence interval (CI): 0.929–0.997, p ConclusionCKD patients, especially MHD patients, were at high risk of suffering sarcopenia. The SARC-F had low-to-moderate sensitivity but high specificity for screening sarcopenia among patients with CKD. The best cutoff values of the SARC-F score were different for screening sarcopenia among NDD-CKD and MHD patients.</p