RESUMEN
Lightweight, high-temperature-resistant carbon-bonded carbon fiber (CBCF) composites with excellent thermal insulation properties are desirable materials for thermal protection systems in military and aerospace applications. Here, glucose was introduced into the polyacrylamide hydrogel to form the glucose-polyacrylamide (Glu-PAM) hydrogel. The CBCF composites were prepared using the Glu-PAM hydrogel as a brand-new binder, and the synergistic effect between glucose and acrylamide was investigated. The results showed the Glu-PAM hydrogel could limit the foaming of glucose and enhance the carbon yield of glucose. Meanwhile, the dopamine-modified chopped carbon fiber could be uniformly mixed by high-speed shearing to form a slurry with the Glu-PAM hydrogel. Finally, the slurry was successfully extruded and molded to prepare CBCF composites with a density of 0.158~0.390 g cm-3 and excellent thermal insulation performance and good mechanical properties. The compressive strength of CBCF composites with a density of 0.158 g cm-3 in the Z direction is 0.18 MPa, and the thermal conductivity in the Z direction at 25 °C and 1200 °C is 0.10 W m-1 k-1 and 0.20 W m-1 k-1, respectively. This study provided an efficient, environment-friendly, and cost-effective strategy for the preparation of CBCF composites.
RESUMEN
Ribosomal protein S6 kinase (S6K) functions as a key component in the target of rapamycin (TOR) pathway involved in multiple processes in eukaryotes. The role and regulation of TOR-S6K in lipid metabolism remained unknown in plants. Here we provide genetic and pharmacological evidence that TOR-Raptor2-S6K1 is important for thylakoid galactolipid biosynthesis and thylakoid grana modeling in rice (Oryza sativa L.). Genetic suppression of S6K1 caused pale yellow-green leaves, defective thylakoid grana architecture. S6K1 directly interacts with Raptor2, a core component in TOR signaling, and S6K1 activity is regulated by Raptor2 and TOR. Plants with suppressed Raptor2 expression or reduced TOR activity by inhibitors mimicked the S6K1-deficient phenotype. A significant reduction in galactolipid content was found in the s6k1, raptor2 mutant or TOR-inhibited plants, which was accompanied by decreased transcript levels of the set of genes such as lipid phosphate phosphatase α5 (LPPα5), MGDG synthase 1 (MGD1), and DGDG synthase 1 (DGD1) involved in galactolipid synthesis, compared to the control plants. Moreover, loss of LPPα5 exhibited a similar phenotype with pale yellow-green leaves. These results suggest that TOR-Raptor2-S6K1 is important for modulating thylakoid membrane lipid biosynthesis, homeostasis, thus enhancing thylakoid grana architecture and normal photosynthesis ability in rice.
Asunto(s)
Galactolípidos/biosíntesis , Regulación de la Expresión Génica de las Plantas , Oryza/genética , Proteínas Quinasas S6 Ribosómicas 70-kDa/genética , Serina-Treonina Quinasas TOR/genética , Tilacoides/genética , Agrobacterium tumefaciens/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Galactosiltransferasas/genética , Galactosiltransferasas/metabolismo , Genotipo , Oryza/metabolismo , Oryza/ultraestructura , Fenotipo , Fosfatidato Fosfatasa/genética , Fosfatidato Fosfatasa/metabolismo , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Hojas de la Planta/ultraestructura , Plantas Modificadas Genéticamente , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Proteínas Quinasas S6 Ribosómicas 70-kDa/metabolismo , Plantones/genética , Plantones/metabolismo , Plantones/ultraestructura , Transducción de Señal , Serina-Treonina Quinasas TOR/metabolismo , Tilacoides/metabolismo , Tilacoides/ultraestructura , Transcripción GenéticaRESUMEN
A broad-band perfect absorber composing a two-dimensional periodic metal-dielectric-metal sandwiches array on dielectric/metal substrate is designed and numerically investigated. It is shown that the nearly-perfect absorption with a bandwidth of about 50 nm in visible region can be achieved by overlapping of two plasmon resonances: one originating from the coupling of electric dipoles between adjacent unit cells and another arising from magnetic dipole plasmon resonances. A capacitor-inductor circuit description is introduced to explain the dependence of resonance frequencies and band-width on geometrical parameters.