RESUMEN
This study investigates the mechanical and piezoresistive sensing properties of recycled carbon-fiber-reinforced polymer composites (rCFRPs) for self-sensing applications, which were prepared from recycled carbon fibers (rCFs) with fiber lengths of 6, 12, 18, and 24 mm using a vacuum infusion method. Mechanical properties of the rCFRPs were examined using uniaxial tensile tests, while sensing characteristics were examined by monitoring the in situ electrical resistance under cyclic and low fatigue loads. Longer fibers (24 mm) showed the superior tensile strength (92.6 MPa) and modulus (8.4 GPa), with improvements of 962.1% and 1061.1%, respectively. Shorter fibers (6 mm) demonstrated enhanced sensing capabilities with the highest sensitivity under low fatigue testing (1000 cycles at 10 MPa), showing an average maximum electrical resistance change rate of 0.7315% and a gauge factor of 4.5876. All the composites displayed a stable electrical response under cyclic and low fatigue loadings. These results provide insights into optimizing rCF incorporation, balancing structural integrity with self-sensing capabilities and contributing to the development of sustainable multifunctional materials.
RESUMEN
The rapid advancement of electrical and telecommunication facilities has resulted in increasing requirements for the development of electromagnetic interference (EMI) shielding composites. Accordingly, an experimental study was conducted to evaluate the EMI shielding performance of carbon nanomaterial (CNM)-embedded carbon-fiber-reinforced polymer (CFRP) or glass-fiber-reinforced polymer (GFRP) composites. Nine combinations of CNMs and carbon or glass fibers were used to fabricate the composites. The synergistic effects of CNMs on the EMI shielding performance were systematically investigated. The results indicated that plate-type CNMs (i.e., graphene and graphite nanoplatelets) have more prominent effects than fiber-type CNMs (carbon nanofibers). The composites fabricated with CFRP afforded higher EMI shielding than the GFRP-based composites. Among the eighteen samples, 3% CNT-GNP in CFRP composites, which included plate-typed CNM, exhibited the best EMI shielding performances, showing 38.6 dB at 0.7 GHz. This study helps understand the shielding performance of CNM-embedded CFRP and GFRP composites in electrical and telecommunication facilities.
RESUMEN
Squamous cell carcinoma (SCC) is the most common malignant head and neck tumor and is responsible for more than 90% of head and neck cancers and accounts for 4.5% of all malignant tumors in males and 3.5% in females in South Korea. The purpose of this study was to investigate the correlation of suggested clinico-pathological prognostic factors such as gender, age, T score (T number in TNM), clinical stage, proliferation, invasion index, and lymph node metastasis to the survival of SCC patients in Korea. Furthermore, cytokeratin (CK), carcinoembryonic antigen (CEA), and recently documented apoptosis related protein, survivin, were analyzed by RT-PCR. In 113 patients, survival curves were estimated by the Kaplan-Meier method and nominal or numeric variable influence on survival was studied by Univariate and Multivariate Regression analysis (Cox proportional hazards model). Univariate analysis demonstrated that gender and age factor had no significant effect on survival rate. T score, on the other hand, significantly influenced survival and univariate analysis demonstrated that Stage 4 group had a significantly lower survival rate than the other stage groups but differentiation and invasion index factors had no significant effect on survival rate. Using a 50% cut-off point, patients with lower PCNA scores showed no survival advantages over those with higher PCNA scores but lymph node metastasis was a significant survival predictor in univariate analysis. In addition, lymph node CK and survivin mRNA expression have significant effects on OSCC patient survival rate. This means that prognostic value can be amplified by coincident analysis of T score, pathologically confirmed lymph node metastasis, and lymph node CK or survivin mRNA expression. Multivariate analysis using Cox's proportional hazards model, clinical TNM stage and lymph node survivin mRNA expression were independent OSCC prognostic factors, which support cancer staging based on the TNM as a powerful prognostic variable and lymph node survivin expression might provide predictive information for OSCC patient survival.