Using a naphthalene-derived mesophase pitch as a starting material, highly oriented ribbon-shaped carbon fibers with a smooth and flat surface were prepared by melt-spinning, oxidative stabilization, carbonization and graphitization. The preferred orientation, morphology and microstructure, as well as physical properties, of the ribbon-shaped carbon fibers were characterized. The results show that, the ribbon-shaped fibers possessed uniform shrinkage upon heat treatment, thereby avoiding shrinkage cracking commonly observed in round-shaped fibers. As heat treatment progressed, the ribbon-shaped graphite fibers displayed larger crystallite sizes and higher orientation of * Corresponding author. Tel.: Fax: +86 27 86556906 E-mail address: xkli8524@sina.com (X. Li) 2 graphene layers along the main surface of the ribbon-shaped fiber in comparison with corresponding round-shaped fibers. The stability of the ribbon-shaped graphite fibers towards thermal oxidation was significantly higher than that of K-1100 graphite fibers.The longitudinal thermal conductivity of the ribbon fibers increased, and electrical resistivity decreased, with increasing the heat treatment temperatures. The longitudinal electrical resistivity and the calculated thermal conductivity of the ribbon-shaped fibers graphitized at 3000°C are about 1.1 μΩ m and above 1100 W/m K at room temperature, respectively. The tensile strength and Young's modulus of these fibers approach 2.53 and 842 GPa, respectively.

In an attempt to evaluate the effects of thermal treatment on wood cell walls (CWs), Masson pine (Pinus massonianaLamb.) wood was thermally modified (TM) at 150, 170 and 190°C for 2, 4 and 6 h, respectively. The chemical properties, cellulose crystallinity (CrI) and micromechanics of the control and thermally modified wood (TMW) were analyzed by wet chemical analysis, X-ray diffraction and nanoindentation. The relative lignin content andCrI increased after the TM partly degraded the amorphous wood polymers. The relative lignin content was higher in TMW and the equilibrium moisture content decreased. Moreover, the elastic modulus (Er) and hardness (H) of TMW were lowered along with the creep ratio decrement (CIT) of CWs. However, a severe treatment (e.g. 190°C/6 h) may negatively affect the mechanical properties of CWs caused by the partial degradation of hemicelluloses and also cellulose.

Ribbon-shaped carbon fibers have been prepared from mesophase pitch by melt-spinning, oxidative stabilization and further heat treatment. The internal graphitic layers of ribbon-shaped carbon fibers graphitized at 2800 °C show a highly preferred orientation along the longitudinal direction. Parallel stretched and unidirectional arranged ribbon-shaped carbon fibers treated at about 450 °C were sprayed with a mesophase pitch powder grout, and then hot-pressed at 500 °C and subsequently carbonized and graphitized at various temperatures to produce one-dimensional carbon/carbon (C/C) composite blocks. The shape and microstructural orientation of ribbon fibers have been maintained in the process of hot-pressing and subsequent heat treatments and the main planes of the ribbon fibers are orderly accumulated along the hot-pressing direction. Microstructural analyses

Tryptophan (Trp) metabolism through the kynurenine pathway (KP) is well known to play a critical function in cancer, autoimmune and neurodegenerative diseases. However, its role in host-pathogen interactions has not been characterized yet. Herein, we identified that kynurenine-3-monooxygenase (KMO), a key rate-limiting enzyme in the KP, and quinolinic acid (QUIN), a key enzymatic product of KMO enzyme, exerted a novel antiviral function against a broad range of viruses. Mechanistically, QUIN induced the production of type I interferon (IFN-I) via activating the N-methyl-d-aspartate receptor (NMDAR) and Ca2+ influx to activate Calcium/calmodulin-dependent protein kinase II (CaMKII)/interferon regulatory factor 3 (IRF3). Importantly, QUIN treatment effectively inhibited viral infections and alleviated disease progression in mice. Furthermore, kmo-/- mice were vulnerable to pathogenic viral challenge with severe clinical symptoms. Collectively, our results demonstrated that KMO and its enzymatic product QUIN were potential therapeutics against emerging pathogenic viruses.

No abstract