Papers by Keyword: LBL

Abstract: Monodispersed Ag nanorods were synthesized using a one-pot synthesis method. These Ag nanorods normally manifest dual surface plasmon resonance (SPR) peaks. This work presents a study of the variation of SPR peaks with variation in the shape of Ag nanorods. Shape variation was achieved through the degradation of a shape-controlling agent (PVP in this work) under white light irradiance with silica passivation to halt further shape variations. This paper also reports the growth & characterization of thin films of the synthesized rod-shaped silver nanoparticles on glass slides along with studies on band pass filter characteristics of the as-synthesized nanoparticles.

Abstract: Polyethylene glycol (PEG), which was not a traditional building block of layer by layer (LBL) self-assembly, was used to fabricate multilayer films by the combination of LBL and magnetic field induction. The UV-abs absorbance of the composite films increases linearly with the number of bilayers, indicating uniform fabrication of each layer. By this method, the multilayers can consist of up to 15 bilayers. The applied magnetic field not only enhances the compactness of the CPC-Fe₃O₄-MMT, but also improves the deposition efficiency of the films. The present method can be an effective method for multilayer film fabrication from non polyelectrolyte.

Abstract: Novel ordered Ultra thin Films (UTFs) based on the hybrid assembly of exfoliated Zn-Cr Layered double hydroxide (LDH) monolayers and typical dawson-type polyoxometalate (POM) anions α-P₂W₁₈O₆₂^6- (P₂W₁₈) were prepared by utilizing a layer by layer (LBL) technique. The structural integrity of the UTFs were characterized by ICP-AES, XRD, IR, UV/DRS, indicating that the Dawson structures remained intact in the hybrid compositions. The morphology and the thickness of the UTFs were evaluated via SEM. The visible light photocatalytic performances of the UTFs were tested in the degradation of aqueous azo dye Congo red (CR). The UTFs showed much higher photocatalytic activity than pure Zn-Cr-NO₃^- LDH, mainly attributed to the improved absorbance and response ability to the visible light.

Abstract: LBL(Long Baseline) positioning provides an important positioning and navigation method for AUV(Autonomous Underwater Vehicle)’s underwater task. Due to the complex underwater acoustic channel, and its poor anti-interference ability, a new feedback Kalman fiter algorithm was present in this paper. By combining travel time information with position information, the state of AUV was estimated accurately. By analyzing experimental results, it showed that the LBL positioning accuracy was improved, and the algorithm ensured AUV complete its autonomous navigation with high precision.

Abstract: Native cellulose nanofibers with high strength ratio may create an alternative as the blade material for wind power field. In this work, cellulose nanofibers (CN) with high L/D ratio was fabricated by combined biological treatment and mechanical disintegration processes. Then, we created a high-performance cellulose layered nanocomposites via layer by layer (LBL) assembling strategy. Transmission electron microscopy (TEM) observations show that common paper pulp exhibits a nearly spherical or amorphous structure, while as-made cellulose nanofibers displays a high aspect ratio, with a length of ca. 10~100 μm and a diameter of ca. 30~100 nm. However, some relative big fibres bundles are still observed. Mechanical measurements demonstrate that the tensile strength, Young’s modulus and elongation at break of layered CN nanocomposites (CNLC) reach 114MPa. 7.0GPa and 68 %,respectively, while only 63MPa, 3.3 GPa and 27 % for layered common paper pulp composites (PFLC). Flexural tests results show that CNLC gives a flexural strength and modulus of 263 MPa and 19 GPa, while only 114 MPa and 11 GPa for PFLC. Fracture surface observations indicate that though layered structure can be observed for both PFLC and CNLC, much thinner layer and long fibrous structure only exist in CNLC, which results in high mechanical performance.

Abstract: Hydrogenated nanocrystalline silicon (nc-Si:H) films produced by layer-by-layer (LBL) deposition technique were studied. The films were grown at different hydrogen to silane flow-rate ratio on crystal silicon (111) substrate. The properties of films were investigated by X-ray diffraction (XRD), micro-Raman scattering spectroscopy, Fourier transform infrared (FTIR) spectroscopy, optical transmission spectroscopy, atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). These properties showed dependence on the hydrogen dilution of silane. Appearance of XRD peaks at diffraction angles of 28.4 o and 56.1 o which correspond to silicon orientation of (111) and (311) respectively, were observed in all films indicating evidence of crystallinity in the films. Raman scattering results indicated that crystallinity in the films was due to the presence of nanocrystallites embedded in an amorphous matrix. The energy gap of the films showed dependence on the hydrogen content in the films. Increase in nanocrystallite size resulted in increase in disorder at low hydrogen dilution films but films remain homogenous with increase in nanocrystallite size for the high hydrogen dilution films.