Key Engineering Materials Vols. 609-610

Abstract: It is very important for micro-fluxgate to reduce its power consumption because higher power consumption causing serious cooling problem which will lead series of questions. In this paper the influence of core film magnetic properties (coercive force Hc and saturation field Hs) on optimum excitation current (OEC) and sensitivity are investigated theoretically. The expressions of optimum excitation magnetic and maximum sensitivity were given. In the field of magnetic material, lower Hc means better soft magnetic properties, but when analyze the effect of Hs and Hc on the OEC and corresponded sensitivity we find that low Hs and high Hc bring low OEC and high sensitivity. Applied magnetic fields at different angles during electroplating and annealing are introduced to improve magnetic properties of electroplated core films. In subsequent experiment we test the OEC, sensitivity, linear range and magnetic noise of fluxgate utilize these core films. Plating with θ=0° (θ is the angle between applied magnetic field and long edge of the core) samples obtain lowest OEC and highest sensitivity, plating with θ=90° and annealed samples obtain large linear range, annealed samples obtain lowest magnetic noise.

Abstract: Monodisperse magnetic microspheres with biomaterial of polylactic acid (PLA) or poly lactic-co-glycolic acid (PLGA) as shell were successfully prepared via T-shaped microchannel reactor in this paper. Hydrophilic ferriferrous oxide (Fe₃O₄) with highly magnetic responsiveness was obtained by solvothermal method. Aqueous solution of Fe₃O₄ was then emulsified into a dichloromethane solution of PLA or PLGA to generate water-in-oil (W/O) emulsion. Different stabilizer, i.e. polyvinyl alcohol (PVA), gelatin or gum arabic, was then added into the W/O emulsion for the purpose of more stable system. Subsequently, W/O/W composite emulsion was formed by injecting W/O emulsion into PVA aqueous solution at the T-shaped joint of microchannel reactor. Magnetic microspheres were finally prepared by solvent evaporation in the microchannel. The characteristic functional groups of Fe₃O₄ were characterized by Fourier transform infrared spectroscopy (FT-IR). The magnetic property was measured with vibrating sample magnetometer (VSM). The morphology of all samples was observed by scanning electron microscopy (SEM). It was found that the magnetic microspheres exhibit a uniform particle size in micro-scale. Therefore, the T-shaped microchannel reactor was expected to create a new approach for fabricating magnetic microspheres.

Abstract: Surface plasmon resonance (SPR) biochemical analysis system began to be developed from the detection and analysis of molecular interactions to the ligand/cell interactions, cell/cell contacts, or cellular reactions. Cells needed be immobilized on the SPR chips based on the penetration depth of surface plasma waves. However it is not easily to fix suspension cells on the bare gold chips. In this paper, an effective method has been developed to immobilize yeast cells on the SPR chip based on a nanoSiO₂ film which was chemically modified. The sensitivity of the SPR chip with a nanoSiO₂ film is 6×10^-7 refractive index unit (RIU), which could meet different applications including cell detection. The whole procedure of cell immobilization has been measured in a lab-free and real-time mode by using our home-made SPR instrument. From the experimental results, the change of the SPR signal of the SPR chip with a modified nanoSiO₂ film is 2.83 times of the bare SPR chip. That means the cell immobilization capability of the modified SiO₂-coating SPR chip is much stronger than that of the bare gold SPR chip, which was also proved by using a microscope. Yeast cells can be effectively fixed on the SPR chip and their immobilization process could be monitored, which hold great potential for the immobilization, detection and further analysis of other suspension cells, such as blood cells.

Abstract: A vertically aligned bioactivity titania nanotube arrays was fabricated on the surface of titanium substrate by anodization. The nanotubes were then treated with optical deposition of silver to make them antibacterial, and to inhibition growth of bacterial in the antibacterial test in vitro. It is shown that the present of silver particle inhibition the growth staphylococcus aureus. Such bioactivity titania nanotube arrays and associated hollow tube structure can be useful as a well-adhered antibacterial bioactive surface layer on titanium implant metals for orthopaedic and dental implants.

Abstract: Chitosan (CS) microspheres loaded with levofloxacin (LOF) were prepared by emulsion crosslinking technique and the experimental parameters were optimized by orthogonal tests. The influences of various factors on the combination properties of chitosan microspheres were discussed. The optimal preparation condition was 98000 chitosan molecular weight, 30mg/ml chitosan concentration, 5:1 volume ratio of oil to water, 1:1 molar ratio of amino group of chitosan to aldehyde group of glutaraldehyde (GA), 1500 rpm stirring rate, 2:1 mass ratio of chitosan to levofloxacin and 1 h crosslinking time. The CS microspheres prepared under optimal parameters had spherical morphology with 1.59 μm of average geometric diameter and 0.99 of span, its loading capacity (LC) and association efficiency (AE) values were 21.71% and 80.49% respectively. In vitro release profile showed the levofloxacin released fast initially, and then slowly from the microspheres with T₉₀ occurring at 188.5h and its delivery behavior conformed to First-Order release kinetics model.

Abstract: Fenton reagent was made by CuFeS₂ ultrafine powders with peroxide, and this Fenton reagent can degrade methylene blue solution with 10 mg/L concentration within 1 min. UV-vis spectra were used to investigate this Fenton reagent's degradation activity of methylene blue.

Abstract: The development of optical fiber transmission technology provides a broad application prospect for the communication of real-time battlefield information. The information could be communicated between the front and headquarters through the cable by using tactical optical fiber communication system, which ensures the missions of military intelligence communicated and tactical real-time arrangement are completed successfully. According to the requirements of multiplexer for military tactical optical fiber communication system, the filters with low-loss have been developed. Filters are prepared by the depositing method of dual ion beam sputtering, Nb2O5 and SiO2 have been chosen as deposition materials, and the filter film is designed and optimized with the help of TFCalc software. In order to broaden the shortwave cutoff region of the filter, the long-wave pass film have been added behind the initial film, and the thickness of the matching layers have been optimized, which based on the concept of equivalent refractive index, the insertion loss of the pass-band of the filter has been reduced. The optical extreme value method and average time method have been used to control layers thickness, and the problem of the layers thickness accuracy controlling have been solved by using the method of real-time calibration of the deposition rate and the repeatability of parameters accurately control. The transmission spectrum of the filter has been tested, which demonstration that the center wavelength of the filter is 1511.2nm, the width of the filters pass band is 17.1nm and 23.5nm in the region of-0.5dB and-35dB respectively, the worst insertion loss within pass band region is-0.1dB, the ripple of the pass band is 0.06dB. The results show that the preparation of the filter meets the using requirements of military tactical fiber optic communication system well.

Abstract: This article presents a design and fabrication method of a embedded cavity using alumina casting-belt. This method is based on HTCC (high-temperature co-fired ceramic) MEMS technology with using fugitive materials. The test structures are fabricated using two different fugitive materialsPolyimide film and ESL4900 film and two different lamination pressures (15MPa and 21MPa). The final stack was sintered by selecting different temperature process parameters in the high-temperature sintering process. Complete the analysis of the sample cavity structure using a SEM (scanning electron microscope). The manufacturing method is available for structural integrity and good air tightness of ceramics sealed cavity and it will be applied to the fabrication of flow sensors, capacitance pressure sensors etc.

Abstract: To prohibit wood hygroscopicity, changing naturally hydrophilic wood surface into hydrophobic surface is essential. To achieve this goal, one possible approach is to coat nanostructured metal oxides on wood surface. In this study, wood surface coated by ZnO nanorod arrsys (ZNAs) was successfully fabricated using a hydrothermal method with subsequent modification by a thin layer of n-dodecyltrimethoxysilane (DTMS). SEM images showed uniformly large-scale ZNAs were grown onto the wood surface. XRD patterns confirmed that the ZNAs were the hexagonal wurtzite phase. The wettability of the ZNAs modified wood sample was evaluated by water contact angle (WCA) measurements. The ZNAs modified wood was found to exhibit superhydrophobicity with a WCA of about 156° and a sliding angle of around 2°, which could resulted from the proper surface roughness and lower surface energy. These results demonstrated that hydrothermal method was a feasible method to create superhydrophobic wood.

Abstract: A series of macropore host-guest catalysts were prepared by third nanoassembly technique. nanoassembly support had a pore volume of 1.32cm³ /g,a specific surface area of 220m²/g, average pore diameter of 27.3nm, the most probable pore diameter of 40nm, a low stacking density of 0.34g/cm³. The results of the XRD and TEM showed that the part of pore was blocked with increasing the amount of active metal. But the aggregation phenomenon was improved by adding uniformly co-impregnant, and the amount of active metal was up to 40%. The lamellar structure of sulfided state metal was formed which the length were between 8 nm to 10 nm and layer were 3~9. Hydrogenation performance of the different catalysts has been evaluated. The removal rates of desulfurization, denitrification, residual carbon and demetalization for hydrotreating in one gram active metal per 100mL volume for FB30 were as 2.0, 2.6, 2.0 and 2.5 times as FC, respectively. The results explained that the macropore host-guest catalyst had higher activity for hydrotreating residue.