Papers by Author: Jie Huang

Abstract: Based on the safety and durability in the cement soil engineering about the pits anti-seepage, embankment impermeable walls and subgrade strengthening in the frozen regions and the retaining walls in foundation pits, the experiments on the compressibility about the cement soil under freezing-thawing cycle, infiltrated and other environmental-action conditions have been carried out and the influential laws of environmental actions on the compression parameter of cement soil have been obtained. The results show that the various environmental actions may have influences on compressibility of cement soil at different levels, and the environmental effects on the compressibility of cement soil in the engineering applications and designs, such as impermeable walls or in the frozen regions, should be taken into account; and the void ratio and the compression parameter will increase with the increase of freezing-thawing cycle times and infiltration time but the compression modulus will decrease with the increase of freezing-thawing cycle times and infiltration time so that the curve regression equation about the void ratio, the compression parameter and compression modulus varying with the freezing-thawing cycle times and the infiltration time has been established. The results are significant and valuable to the safety and the durability of cement soil engineering.

Abstract: The use of metallic nanoparticles in the field of orthopaedics as antimicrobial components of coatings is receiving particular attention. An innovative approach has been developed whereby various metal/metal oxide nanoparticles are used to prevent infection occurring on the surface of prostheses. In this study nano metallic oxides (zinc oxide - ZnO and tungsten oxide - WO₃) were used. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of each nanoparticulate were determined against four species of bacteria (Staphylococcus aureus, Escherichia coli, Staphylococcus epidermidis and Pseudomonas aeruginosa). Subsequently the nanoparticles were prepared in a suspension of ethanol and sprayed onto the surface of glass using electrohydrodynamic deposition. Quantitative assessments as regards the antimicrobial properties of these coated samples were carried out. Comparisons of the antibacterial properties demonstrated that 2500 µg/ml or above of the oxides were required to kill the species of bacteria tested. WO₃ was the most effective oxide tested in suspension using growth inhibition tests. However, coated samples demonstrated that ZnO was more bactericidal than WO₃ under these conditions.

Abstract: Dense and porous HA and Si-HA discs and granules with varying percentages of silicon substitution have been produced and physically and chemically characterised using scanning electron microscopy, surface area analysis, porosimetry, density measurement, image analysis, Xray diffraction, X-ray fluorescence, FT-infrared spectroscopy and in-vitro and in-vivo testing. Results have shown that cell adhesion in-vitro and bone apposition in-vivo are enhanced by the presence of silicon substitution in the hydroxyapatite structure. The biological response to the materials appears to indicate an optimum outcome for levels of silicon substitution of 0.8wt%.

Abstract: Fine nanoapatite relics were deposited on glass substrates by electrohydrodynamic atomisation, using nanohydroxyapatite (nHA), nano-carbonated hydroxyapatite (nCHA) and nanosilicon- substituted hydroxyapatite (nSiHA) suspensions. These electrosprayed nanoapatites were evaluated in-vitro using simulated body fluid (SBF) and human osteoblast (HOB) cells. The SBF study revealed that newly-formed apatite layers were observed on the surface of the relics. Furthermore, enhanced HOB cell growth was observed on each of the nanoapatites at all time points. Hence, this work demonstrated that electrosprayed nanoapatites offer considerable potential as biomaterials.

Abstract: Topography of the surface plays an important role in cellular responses. A novel method, called template-assisted electrohydrodynamic atomization (TAEA) spraying, was developed to create surface topography of hydroxyapatite (HA) on metallic surfaces. In this work, by varying the core process parameters (e.g. flow rate, applied voltage and distance between substrate and needle), the optimization and development of the TAEA process with nanoHA suspension is investigated with the aim of preparing a nanostructured HA coating with patterning of high resolution for biomedical applications.

Abstract: A Bioglass® reinforced polyethylene (Bioglass®/polyethylene) composite has been prepared, which combines the high bioactivity of Bioglass® and the toughness of polyethylene. The spatial distribution of Bioglass® particles within the composite is important for the performance of composites in-vivo. Recent developments in X-ray microtomography (XμT) have made it possible to visualize internal and microstructural details with different X-ray absorbencies, nondestructively, and to acquire 3D information at high spatial resolution. In this study, the volume fraction and 3D spatial distribution of Bioglass® particles has been acquired quantitatively by XμT. The information obtained provides a foundation for understanding the mechanical and bioactive properties of the Bioglass®/polyethylene composites.

Abstract: Bioceramic fibres, scaffolds and mats are important structures in biomedical applications. Electrohydrodynamic routes are relatively new for processing advanced materials and in this paper we use electrospinning to prepare zirconia fibres diameter down to 200nm and hydroxyapatite (HA) fibres down to 1$m. Zirconia-polymer and nHA-polymer composite scaffolds structures (mats) with 400-1000 $m windows were also prepared.

Abstract: Nano-sized HA (nHA) was applied to the surface of glass and titanium substrates using electrostatic atomisation spray (EAS) deposition. The phase purity of nHA was confirmed by X-ray diffraction. The nHA suspension consisted of rod–like particles 20-30nm in width and 50-100nm in length. The viscosity and conductivity of nHA suspension were 321 mPa s and 5.6 x 10-4 S/m, respectively. EAS of nHA in cone-jet mode was achieved at flow rate of 10-9 m3s-1 with the applied voltage between the needle and the ring-shaped ground electrode of ~6 kV. Micrometer- to submicrometerscaled nHA islands were successfully deposited on the substrate surface. Image analysis showed that the area percentage of nHA increased with deposition time, it covered 50% of the surface area after 10s of spraying. Partial dissolution of nHA was observed after immersion in deionised water for 1 month, particularly on the submicrometer sized nHA islands. Formation of a bone-like apatite layer was found after incubation in simulated body fluid (SBF K9) for 5 days, indicating the high bioactivity of the nHA deposits. In vitro culture with human osteoblast cells showed that the nHA islands were able to support the growth of HOB cells during 7 days of culture; the HOB cell activity increased with culture time as well as EAS deposition time. Immunofluorescence study showed that HOB cells expressed well-organised actin stress fibres on nHA deposited surfaces after 3 days of culture. The result indicated that nHA deposition provided more favourable surfaces for cell attachment. Therefore, electrostatic atomization spray deposition of nHA offers great potential for the creation of bioactive surfaces on bioinert implant surface to provide improved interfacial bonding with host tissues.

Abstract: Nanostructured hydroxyapatite (nHA) thin coatings of thickness 0.5 µm have been successfully produced using a radio-frequency magnetron sputtering technique, through careful selection and control of the processing conditions. nHA coatings were immersed in simulated body fluid (SBF) to determine the rate of nucleation and growth of an apatite layer on their surface. A dense, newlyformed apatite layer with similar characteristics to that of the biological bone apatite, was observed after 7 days of immersion in SBF. X-ray diffraction and infrared analyses confirmed this layer to be calcium-deficient nanocrystalline carbonate HA. All these results demonstrated that the novel nHA coatings were highly bioactive, and the time-frame required to form a dense apatite layer was reduced significantly as compared to the micrometer-sized, sintered HA pellets (from 28 days to 7 days).

Abstract: Silicon-substituted hydroxyapatite (SiHA) attracts particular interest due its enhanced bioactivity compared with pure hydroxyapatite. In this study we seek to clarify the effects on the lattice parameters of both composition and sintering temperature in experimentally-produced HA and 0.8wt% SiHA, 1.5wt% SiHA and 2.0wt% SiHA sintered at 800oC and 1200oC. X ray diffraction was used to determine the phase purity and crystallographic structure. We found that while the c parameter increased with increasing silicon concentration, the a parameter decreased with initial silicon incorporation then recovered with further increases in silicon incorporation. The calcium (2) channel expanded with silicon incorporation while tetrahedron distortion index (TDI) and the radius of the P channel showed a similar dependence on silicon content as the a parameter.