Advanced Materials Research Vol. 465

Abstract: Regenerated Antheraea Pernyi silk fibroin (ASF) solution was prepared by dissolving Antheraea Pernyi (A. pernyi) silk fiber in lithium thiocyanate solution. Atomic force microscopy (AFM) examination showed that there were many short nanofibers in regenerated ASF solution, which were made up of 10-20 nm nanospheres. In this paper, we discussed the formation mechanism of these nanofibers. The results of the surface tension showed that ASF had surface active and can significantly decline the surface tension of water from 73 mN/m to 51 mN/m. The hydrophobic side chains of ASF molecular would try to break away from water environment and thereby undergo self-assembly into nanospheres. And then, these nanospheres arrange into a short nanofiber. Then, the ASF nanofiber film was prepared by casting regenerated ASF solution blended with glycol. The structure of ASF was β-sheet and the film was water-insoluble. This blend film not only had excellent mechanical properties, but also can be biodegradated by enzyme in vitro. All of this indicated that this new regenerated ASF nanofiber film not only provided excellent biocompatibility, but also had large surface as extracellular matrix (ECM) to cell adhesion. The film made of nanofiber was similar to ECM on the nanoscale, which promoted cell migration and proliferation. In summary, it provided a great potential as a biological material.

Abstract: Anatase TiO2- thin films on glass substrates were prepared by sol-gel dip-coating method. We designed a multi-round annealing process which was under the air pressure of 5 Pa and then 5×10-2 Pa for one hour each at 550 °C, and such process was repeated for three times. The special designed annealing process can obviously improve the conductivity of the udoped TiO2- thin films. The minimum resistivity of the undoped TiO2- thin films reached 0.8 Ω cm after being treated by the multi-round annealing process. It was demonstrated that such annealing process was an effective way to increase the defects in TiO2- thin films such as oxygen vacancies. The average transmittances of the films were approximately 60~80% in the visible range with the forbidden gaps of 3.25~3.35 eV. After the multi-round annealing process, the optical forbidden gaps of the films became narrowed slightly, which might be also related to the defects introduced during the multi-annealing process.

Abstract: In this paper, we investigate theoretically the coupling characteristics of two identical microfibers or nanofibers (MNFs) with different ambient refractive indices. The results show that, compared with weakly coupled waveguides, coupled two MNFs can provide a much smaller coupling length without sacrificing high coupling efficiency. This feature is helpful for studying and developing microphotonic or nanophotonic devices with MNFs.

Abstract: Monodisperse polyethylene glycol (PEG) microspheres were prepared using microfluidic chips coupled with photopolymerization technique. Based on sheath effect in T-junction microfluidic channels, dispersions of uniform PEG prepolymer droplets in silicon oil are formed. The diameters of the formed PEG prepolymer droplets in the dispersions were controlled very well by altering the relative sheath/sample flow rate ratios. After photopolymerization under UV exposure, the uniform PEG prepolymer droplets isolated by silicon oil underwent photocrosslinking and became monodisperse PEG microspheres.

Abstract: Two different types of morphology are observed in synthesis of SiC nanowires by catalyst-assisted pyrolysis of polymeric precursor while Au acts as the catalyst. Both two types of SiC nanowires are well oriented and uniform in diameter. The results indicate that longer (~20 μm) and slimmer (~100 nm) nanowires are tends to be produced in high temperature (1450°C), while shorter (~10 μm) and thicker (200~300 nm) ones are tends to be produced in low temperature (1420°C). Then we make a discussion on the mechanism of the growth of SiC nanowires based on the VLS (Vapor-Liquid-Solid) process.

Abstract: Star-like CuO with submicrometer sizes was fabricated via a simple liquid-phase deposition with the assistant of PVP and Na₂MoO₄. The as-prepared CuO have been characterized by X-ray diffraction(XRD) and scanning electron microscopy (SEM). The results showed that the as-prepared CuO owned monoclinic structure, the concentrations of PVP, Na₂MoO₄ and NaOH are very important to the morphology of CuO. The quality of PVP impacts the formation of thin flakes on the skeletons. Meanwhile, the growth of dendritic skeletons was depended on the addition of Na₂MoO₄, and the effect of NaOH is to control the dimension of CuO structure.

Abstract: In this work, F-Sb codoped SnO₂ film electrode material has been prepared and used as an anode on titanium (Ti) substrate for degradation of methyl orange. The emphasis is laid on the effect of univalent cations fluoride doped during preparation of F-Sn codoped SnO₂ composites by sol gel method. The facts show that univalent cations fluoride could affects the electro-catalytic degradation rate of methyl orange by F-Sb codoped composite film on the Ti electrode. A promotion to the degradation rates of methyl orange could be observed when KF or NH₄F was used as codopant but other fluoride codopant such as LiF, NaF or HF could slow the methyl orange degradation. X-ray diffraction (XRD) and x-ray photo-electron spectroscopy (XPS) were used to study structures and composition of the anode surface.

Abstract: Cerium (Ce) and antimony (Sb) codoped tin dioxide (SnO₂) films (Ce:Sb:Sn=2:3:95 molar ratio) have been prepared on the surface of titanium (Ti) substrate by sol-gel method. A self-assembled layer (SAL) of dodecyl thiol with cholesterol was formed on the surface of Ce-Sb codoped SnO₂ films/Ti electrode. The SAL was then used with the cholesterol as the template forming the molecular imprinting layer. The extraction of cholesterol has resulted in formation of sites in the layer of dodecyl thiol which could have been used as channels for the ferro-ferric cyanide coupled redox reaction to quantify recombining cholesterol on the sites. This sensor prototype could detect cholesterol concentrations between 40 and 60 μM. X-ray diffraction (XRD) and scanning electron microscopy (SEM) have been used to analyze the structure and morphology of the samples.

Abstract: Surface NH2-functionalized SBA-15 mesoporous silica was synthesized using toluene diisocyanate (TDI) as bridge molecule. Firstly, surface Si-OH of SBA-15 reacted with one –NCO group of TDI molecular. Then, another unreacted –NCO group of TDI molecular reacted with one -NH2 group of ethylenediamine (EDA). Finally, NH2- group was successfully grafted on mesoporous SBA-15 surface by the above two step method. XRD, N2 adsorption/desorption analysis, FTIR and 29Si MAS NMR were used to identify the well-ordered structure and the successful incorporation of -NH2 on the surface of the synthesized materials. Characterizations revealed that such -NH2 graft is an effective method to obtain a high loading of amino on SBA -15.

Abstract: In this work, nickel glycolate polymer microtubes (NGPMs) were prepared via a facile solvothermal method using hydrous nickel nitrate and anhydrous sodium acetate as starting materials, and ethylene glycol as solvent. Furthermore, nickel oxide (NiO) microtubes were obtained by a high-temperature treatment of NGPMs in air atmosphere. The morphology and phase of the products were characterized by scanning electron microscope (SEM), Transmission electron microscope (TEM) and X-ray diffractometer (XRD). The results show that NGPMs are of hierarchical structure, which are composed of a lot of nanolamellas. The morphology of NiO microtubes directly derived from that of NGPMs. In addition, the experiments were conducted with atomic absorption spectrometer for adsorption of Cr2O72- in ultrapure water using these microtubes obtained as absorbers. The results reveal that NGPMs obviously possess a better ability of chromium absorption with a maximum absorbing value of 14.6 mg/g at pH of 4 than NiO microtubes. Thus, the as-prepared of NGPMs may be promising as a new type of absorber for heavy metal ion for water treatment.