A novel multifunctional biomedical material based on polyacrylonitrile:preparation and characterization

Wet spun microfibers have great potential in the design of multifunctional controlled release materials. Curcumin (Cur) and vitamin E acetate (Vit. E Ac) were used as a model drug system to evaluate the potential application of the drug-loaded microfiber system for enhanced delivery. The drugs and polyacrylonitrile (PAN) were blended together and spun to produce the target drug-loaded microfiber using an improved wet-spinning method and then the microfibers were successfully woven into fabrics. Morphological, mechanical properties, thermal behavior, drug release performance characteristics, and cytocompatibility were determined. The drug-loaded microfiber had a lobed “kidney” shape with a height of 50 ~ 100 μm and width of 100 ~ 200 μm. The addition of Cur and Vit. E Ac had a great influence on the surface and cross section structure of the microfiber, leading to a rough surface having microvoids. X-ray diffraction and Fourier transform infrared spectroscopy indicated that the drugs were successfully encapsulated and dispersed evenly in the microfilament fiber. After drug loading, the mechanical performance of the microfilament changed, with the breaking strength improved slightly, but the tensile elongation increased significantly. Thermogravimetric results showed that the drug load had no apparent adverse effect on the thermal properties of the microfibers. However, drug release from the fiber, as determined through in-vitro experiments, is relatively low and this property is maintained over time. Furthermore, in-vitro cytocompatibility testing showed that no cytotoxicty on the L929 cells was found up to 5% and 10% respectively of the theoretical drug loading content (TDLC) of curcumin and vitamin E acetate. This study provides reference data to aid the development of multifunctional textiles and to explore their use in the biomedical material field

Electronic and optical properties of graphane, silicane, MoS 2 homo-bilayers and hetero-bilayers

Abstract(#br)The electronic and optical properties of graphane, silicane and MoS 2 bilayers, as well as the graphane/MoS 2 and silicane/MoS 2 hetero-bilayers, are calculated by the first-principles method. The interlayer interactions of all the bilayer systems are shown to be mainly van der Waals. Both the graphane/MoS 2 and silicane/MoS 2 hetero-bilayers belong to the type-II heterostructure, which can be utilized in photo-voltaic devices due to the efficient spatial separation of electrons and holes. For optical properties, the distinctions for the imaginary parts of the dielectric function ε 2 ( ω ) between the monolayer and bilayer systems for both the graphane and silicane are more evident in electric vector E|| z. However, the differences between ε 2 ( ω ) of the monolayer and bilayer MoS 2 materials are more significant in E|| x. Broader light absorption ranges of the hetero-bilayers are reached, which can also improve the charge separation of the electron-hole pairs

Development of a 1-THz 4th-harmonic gyrotron

A design of a 1-THz 4th Harmonic Gyrotron is proposed in this paper. Fourth harmonic interaction is adopted to lower the strength of the external magnet. The magnet can be as low as 10T. Such a low-intensity magnetic field can be easily proposed by a superconduct magnet, which make the generation of continuous waves at 1 THz possible. Seeing that the mode competition is extremely fierce, a large orbit gun is employed as the driven source. An 80-kV, 0.7-A electron beam is injected into the interaction circuit to excite the fourth-harmonic electromagnetic waves. According to the cold dispersive diagram, the TE4, 8 mode of the cylindrical waveguide is selected as the operating mode to further suppress the mode competition induced by the fundamental modes, the 2nd harmonic modes and the 3rd harmonic modes. It could be inferred based on the multi-mode time-domain theory that an output power of 1.15 kW can be achieved. The scheme diagram for the hot test is proposed. The LOG is chosen as the electron gun. Particular structure is employed for improving the output efficiency in the interaction circuit

Cyclic threshold shear strain for pore water pressure generation and stiffness degradation in marine clays at Yangtze estuary

Cyclic threshold shear strain is a fundamental property of saturated soils under cyclic loading. To investigate the cyclic threshold shear strain for pore water pressure generation (γtp) and stiffness degradation (γtd), a series of strain-controlled multistage undrained cyclic triaxial tests were carried out on in-situ saturated marine clay in the Yangtze estuary with different plasticity index Ip. The test results show that both γtp and γtd increase with increasing Ip, and γtp is larger than γtd for the same marine clay tested under the same conditions, with γtp = 0.017 ~ 0.019%, γtd = 0.008 ~ 0.012% for Ip of 17, γtp = 0.033 ~ 0.039%, γtd = 0.020 ~ 0.025% for Ip of 32, and γtp = 0.040 ~ 0.048%, γtd = 0.031 ~ 0.036% for Ip of 40. Moreover, the development of stiffness degradation may not necessarily require the generation of pore water pressure but can be aggravated by it. Furthermore, the γtp and γtd of marine clay are compared with terrestrial soils and marine clays cited from the published literature, the results indicate that the special marine sedimentary environment and the combined action of flow and tidal wave system cause the γtp and γtd of marine clay in the Yangtze estuary to be smaller than that of the terrestrial clays and marine clays in other sea areas

Design of an ultra-low spread magnetic cusp gun based on the compensation principle

In this paper, a design of a magnetic cusp gun with ultra-low velocity spread is proposed. Based on the Lagrange mechanics, the spread in the generalized angular momentum and the spread in guiding center radius can compensate each other for low velocity spread