Advanced Materials Research Vol. 906

Abstract: Zinc and iron oxide nanoparticles were synthesized using natural bio-polymeric templates viz. cellulose and sodium alginate. Cellulose fibres from different sources viz. filter-and blot-papers, were used as templates for this purpose. The synthesized Zinc oxide nanoparticles were characterized by X-ray diffraction (XRD), fourier transform infra-red spectra (FT-IR), UV-Visible spectrophotomer (UV-Vis) and scanning electron microscopic (SEM) studies. XRD studied confirmed the formation of highly crystalline hexagonal wurtzite phase of ZnO in all the synthesized nanoparticles. The average crystallite sizes of the nanoparticles obtained using different templates, were well below 50 nm. Characteristics of the zinc oxide nanoparticles obtained by template-based techniques were compared with those obtained by co-precipitation technique. Influence of various templates on the characteristics of metal oxide nanoparticles was studied.

Abstract: The CuS nanoparticles precursor have been synthesized by microwave irradiation, using copper nitrate and thioacetamide (TAA) as raw materials, dodecyl sodium sulfate as surfactants. After the precursor had being split with n-butyl lithium for 14 days, we synthesized w-doped copper sulfide nanoparticles with microwave hydrothermal method. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectra.

Abstract: Indium vanadate nanocrystalline was prepared by Indium chloride, vanadium (V) oxide as raw materials and sodium dodecyl sulfate as surfactant under microwave irradiation. The sample was characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM). We studied the photocatalytic activity of the as-prepared samples using degradation of methyl orange in visible light. It shows that the photocatalytic activity of Indium vanadate nanocrystalline was very well. It found that when the catalyst calcined at 773 K was 0.10 g, and 0.3 mL hydrogen peroxide joined as well as pH was 2.0, the degradation ratio of InVO₄ for methylene orange of 100 mL 2 mg/L reached 75% in 50 min.

Abstract: Gold and silver nanostructures (such as Au nanorods and Ag nanoplates) exhibit strong and tunable surface plasmon resonance in the near-infrared region (NIR). Under a certain NIR laser irradiation, noble metal nanostructrues achieve a high photo-thermal effect, which would be useful in the therapy. In this work, Au nanorods with longitude surface plasmon resonance (SPR_L) shifting in the region of 650 ~1100 nm were synthesized by a seed method. Ag nanoplates and nanocubes with SPR located in the region of 650~850 nm were produced by a hydrothermal method. Through adjusting laser power and irradiating time, the photo-thermal conversions of these nanostructures were studied under NIR laser irradiation. Under low power laser (808 nm, <1W) irradiation, the shape of the Au nanorods are stable and the temperature of colloid increase from room temperature to ~57°C. However, Au nanorods undergo deformation from rod to spherical particle under irradiation of high power (808 nm laser; 6W; 1064nm laser, 7W), resulting in the disappearance of SPR_L. Morphology evolutions and photo-thermal conversion of Ag nanostructures were also studied. Ag nanostructures have a lower photo-thermal conversion compared with that of Au nanorods colloid. Snipping and dendrite can be observed for Ag nanoplates after irradiating, while Ag nanocubes have no obvious shape change.

Abstract: To develop novel biocomposites, three different silk-fibroin fabrics (plain woven fabric, plain weft-knit fabric and non-woven fabric) were, respectively, blended with poly (ε-caprolactone) (PCL) by a solution blending method. The effects of various fabric structures on the mechanical and microstructure properties of silk-fibroin fabric reinforced (SF-fabric-reinforced) PCL biocomposites were investigated. It was obvious that the breaking strength and elongation of SF-fabric-reinforced PCL biocomposites decreased while the Youngs modulus increased. Scanning Electron Microscopy (SEM) photographs showed that silk-fibroin fabrics were well bonded with PCL matrix. From Wide-Angle X-ray Diffraction (WXRD) analysis, plain woven and plain weft-knit fabrics showed higher ability to increase the crystallinity of PCL matrix compared with non-woven fabric.

Abstract: The electrospun scaffold plays a crucial role in tissue engineering for its unique structure which can mimic the structure and biological functions of the natural extracellurlar matrix (ECM). This study discuss the effects of electrospinning parameters, such as applied voltage, tip-collector distance, DMF content percentage and polymer concentration, on the porosity and the surface area of electrospun fibrous scaffolds. The results show that the fiber diameter of electrospun scaffold can be increased with the lower applied voltage, the shorter the tip-collector distance, the smaller DMF content percentage or the higher the polymer concentration. The PCL electrospun scaffolds have high porosity ranging from 85.5 to 92.4%. Furthermore, the surface area to volume ratio exhibits a clear relationship with the fiber diameter. The surface area can be improved through decreasing the diameter of nanofibers.

Abstract: Titanium-based composites containing Ti_xP_y phase (s) or CaTiO₃ and Ti_xP_y phase (s) were produced by a non conventional method using suitable mixtures of TiH₂ powder and phosphoric acid (TiH₂/P), or TiH₂ and 10 vol.% of calcium phosphate (TiH₂/CP), respectively. The composites were produced with the same phosphor molar concentration. The mixtures were prepared by ultrasound in water, dried in a rotary evaporator, pressed at 600 MPa and vacuum-sintered at 1200 °C for 2 hours. The mixtures were well dispersed by ultrasound and agglomerate-free. The analyses show that titanium particles were coated with Ti_xP_y phase (s) for the TiH₂/P composite or with an intermediary layer of Ti_xP_y phase (s) and an external deposit of calcium titanate for the TiH₂/CP composite. The TiH₂/P composite presented higher compressive strength and about the same contact angle compared to the TiH₂/CP composite. However, both materials displayed lower contact angle than that of pure titanium.

Abstract: Three kinds of carbonaceous materials with different structural and chemical properties, Carbon Black (CB), Multi-walled Carbon Nanotubes (MWNTs), and Graphene Oxide (GO), were well suspended in sodium alginate (SA) solutions, and the suspension rheological behaviors were investigated in details. Steady rheological results showed that the suspensions exhibited same shear-thinning behaviors as SA solution. Dynamic rheological results showed that the complex viscosity (η^*) was similar to that of steady rheological measurement, and both SA solution and SA/carbonaceous materials suspensions exhibited liquid-like behaviors, confirmed by the loss modulus larger than the storage modulus. The loss factor tanδ remarkably decreased for SA/GO solution compared with SA/CB and SA/MWNTs suspension at the same concentration, indicating the increase of elasticity via interactions between the GO and SA.

Abstract: In this paper, in vitro degradation behaviors of the PDO monofilaments and the stents were studied. The mechanical properties,morphology observation and Differential Scanning Calorimeter (DSC) of PDO monofilaments were determined, as well as the compression strength of the stents. The experimental results showed that the PDO monofilaments contained half of its original strength after 6 weeks degradation and lost its strength in the 10^th week. DSC outcomes showed that the crystalline regions of PDO havent been hydrolyzed after 16 weeks of degradation. The stents demonstrated good compression behaviors for 12 weeks and therefore can be utilized in short-term application.

Abstract: Cast aluminium alloys are being employed increasingly in the automotive sector due to their light weight and excellent castability. This paper focuses on the strain hardening behaviour of Hipped and non-Hipped components of cast aluminium alloy 354 subjected to two-step ageing, as opposed to the routinely carried out single-step ageing. First step ageing (at 100°C) was carried out for 2 h and 5 h; ageing time at second step (at 170°C) was 1, 2 and 5 h. Mechanical properties and strain hardening behaviour were evaluated for different variants of two-step ageing treatment. Analysis of the results shows that the Hipped components have higher hardening capacity and generally higher strain hardening rate compared to the non-Hipped ones. Some of the two-step ageing treatments give mechanical properties comparable to the conventional T61 treatment, but with significantly higher strain hardening rate.