Frequency-Dependent Dielectric Permittivity and Water Permeability in Ordered Mesoporous Silica-Grafted Fluorinated Polyimides.

Polymers with a low dielectric constant (Dk) are promising materials for high-speed communication networks, which demand exceptional thermal stability, ultralow Dk and dissipation factor, and minimum moisture absorption. In this paper, we prepared a series of novel low-Dk polyimide films containing an MCM-41-type amino-functionalized mesoporous silica (AMS) via in situ polymerization and subsequent thermal imidization and investigated their morphologies, thermal properties, frequency-dependent dielectric behaviors, and water permeabilities. Incorporating 6 wt.% AMS reduced the Dk at 1 MHz from 2.91 of the pristine fluorinated polyimide (FPI) to 2.67 of the AMS-grafted FPI (FPI-g-AMS), attributed to the free volume and low polarizability of fluorine moieties in the backbone and the incorporation of air voids within the mesoporous AMS particles. The FPI-g-AMS films presented a stable dissipation factor across a wide frequency range. Introducing a silane coupling agent increased the hydrophobicity of AMS surfaces, which inhibited the approaching of the water molecules, avoiding the hydrolysis of Si-O-Si bonds of the AMS pore walls. The increased tortuosity caused by the AMS particles also reduced water permeability. All the FPI-g-AMS films displayed excellent thermooxidative/thermomechanical stability, including a high 5% weight loss temperature (>531 °C), char residue at 800 °C (>51%), and glass transition temperature (>300 °C).

A New Class of Carbon Nanostructures for High-Performance Electro-Magnetic and -Chemical Barriers.

It is of importance to explore a new carbon nanomaterial possessing vital functions to fulfill the high standards for practical achievement of the electromagnetic (EM) barrier for blocking EM waves and the electrochemical (EC) barrier as a functional separator for EC energy storage. Herein, facile synthesis of a new class of carbon nanostructures, which consist of interconnected N-doped graphitic carbon nanocubes partially embedded by nickel nanoparticles, is described. The hollow interior of graphitic nanocube induces internal reflection of EM waves and confines active materials of EC energy storage. Nitrogen functionalities implanted in graphitic structure enhance electrical conductivity as well as improve chemical interaction with active materials. Furthermore, nickel nanoparticles in graphitic nanocube function as an EM wave-absorbing material and an electrocatalyst for EC energy storage. Through comprehensive assessments, remarkable performances originating from distinctive nanostructures give new insights into structural design for the carbon nanostructure-based high-performance EM and EC barriers.

Clinical implications of thrombocytosis in acute phase Kawasaki disease.

In Kawasaki disease (KD), thrombocytosis is commonly found in the subacute phase. However, the exact significance of thrombocytosis in the acute phase of KD is unclear. To evaluate serum platelet counts in patients during the acute phase of KD and assess the clinical outcomes according to the degree of thrombocytosis, we collected data of KD patients between 2009 and 2017. A total of 505 patients with KD were enrolled, and 249 (49.3%) patients had thrombocytosis, including mild (69.5%), moderate (21.7%), severe (4.8%), and extreme (4.0%) thrombocytosis. Correlation analysis revealed a positive correlation between the maximum platelet count and admission duration (r = 0.359, p < 0.001) and fever duration (r = 0.204, p < 0.001). The maximum platelet count was significantly higher in IVIG non-responders than that in IVIG responders (629 ± 201 × 109/L vs. 499 ± 154 × 109/L, p < 0.001), and in patients with coronary artery dilatation (CAD) than in those without CAD (602 ± 201 × 109/L vs. 512 ± 164 × 109/L, p < 0.001).Conclusion: Thrombocytosis in acute phase KD was associated with poor clinical outcomes such as IVIG non-responsiveness, CAD, and prolonged admission and fever durations. What is Known: • Thrombocytopenia in the acute phase of KD is related to non-responsiveness to IVIG and the risk of coronary artery dilatation. • The exact significance of thrombocytosis in the acute phase of KD as a benign phenomenon or a signal of poor outcome of KD is unclear. What is New: • Thrombocytosis in acute phase KD was associated with poor clinical outcomes such as IVIG non-responsiveness, CAD, and prolonged admission and fever durations.

Survival and Prognosis of Patients with Pilocytic Astrocytoma: A Single-Center Study.

BACKGROUND: Pilocytic astrocytoma (PA) is a brain tumor that is relatively more common in children and young adults. METHODS: We retrospectively reviewed the medical records of patients with PA treated at a single center between 1988 and 2018. RESULTS: We included 31 subjects with PA. The median age at diagnosis was 13.4 years, and the median follow-up duration was 9.9 years. The total PA group had a 10-year disease-specific survival (DSS) rate of 92.6% [95% confidence interval (CI), 82.6-100] and 10-year progression-free survival (PFS) rate of 52.8% (95% CI, 32.0-73.6). In patients aged <20 years, tumors were more likely to be located in sites in which gross total tumor resection (GTR) was impossible. No statistically significant difference in 10-year DSS was found between the GTR (100%) and non-GTR (89.7%; 95% CI, 76.2-100; p=0.374) groups. However, a statistically significant difference in 10-year PFS was found between the GTR (100%) and non-GTR groups (30.7%; 95% CI, 8.6-52.8; p=0.012). In the non-GTR group, no statistically significant difference in 10-year DSS was found between the patients who received immediate additional chemotherapy and/or radiotherapy (Add-Tx group, 92.9%; 95% CI, 79.4-100) and the non-Add-Tx group (83.3%; 95% CI, 53.5-100; p=0.577). No statistically significant difference in 10-year PFS was found between the Add-Tx group (28.9%; 95% CI, 1.7-56.1) and non-Add-Tx group (33.3%; 95% CI, 0-70.9; p=0.706). CONCLUSION: The PFS of the patients with PA in our study depended only on the degree of surgical excision associated with tumor location. This study is limited by its small number of patients and retrospective nature. A multicenter and prospective study is necessary to confirm these findings.