Advanced Materials Research Vol. 1119

Abstract: A biodegradable cross-linked polyester, poly (1, 8-octanediol-glycerol-dodecanedioate) (POGDA) was prepared from 1, 8-octanediol (Oct), glycerol (Gly) and dodecanedioic acid (DA) without any catalyst. One of the factors, molar ratio of monomers greatly affects the material properties of POGDA and the effect was evaluated. Result showed that the glycerol acts as cross-link agent. When the molar ratio of glycerol increased, the gel content of POGDA became higher. POGDA has a range of glass transition temperature (T_g) with different monomers’ molar ratio. Exist of melting point (T_m) indicated the crystallline region in the polymer. POGDA with low molar ratio of glycerol has high T_m due to the bigger region of crystal. In vitro degradation was performed to investigate the biodegradation behaviour of POGDA. The polymer with tunable material properties by tailoring monomers’ molar ratio is expected to have broad application in medical fields such as drug delivery systems and tissue engineering.

Abstract: In this research, sol-gel method was utilized to prepare ceramic coating on medical grade 316 L stainless steel with different annealing temperature, solution constitute and coating layers. As-prepared zirconia film morphology was characterized by scanning electron microscope. The human umbilical vein endothelial cells (HUVECs) were cultured on specimens to evaluate their biocompatibility, with fluorescence staining to observe the morphology of cells. The results showed that annealed zirconia film was improved mechanical properties. According to the bio-evaluation results, HUVECs shows very small difference on proliferation activity on ZrO₂ coatings compared to 316 L stainless steel, which was shows high difference on proinflammation response test. This indicated that ceramic coating can be indeed less aggressive, which was use for potential future application in surface treatment of stainless steel in scalpels and indwelling needle.

Abstract: Microencapsulation forms an integral part in synthesizing bioinspired materials. This paper focuses on elaborating the problems faced in encapsulation of DGEBA microcapsules in PMMA and urea formaldehyde shell wall. The preparation process and the process parameters affecting the microcapsule property are discussed. The difference between the microcapsules prepared using emulsion polymerization and that by solvent evaporation has been discussed. The size, shape and morphology of the microcapsules was characterized using FESEM technique. It was observed that the agglomeration of the microcapsules can be prevented by changing the concentration of the emulsifier. However, in case of urea formaldehyde encapsulation chunks of pre-polymer resulted in agglomeration of the nanosized capsules even if higher concentration of emulsifier was implemented.

Abstract: The purpose of this study was to evaluate the chemical and metallurgical aspects, mechanical properties and hardness of the Co-Cr alloy powders manufactured by sintering process DMLS and compared with Ni-Cr alloys used for personalized dental crowns.In dentistry are develop new methods to obtain personalized dental crowns quickly, the cost is not expensive and is identically with the dental scan realized by dentist. DMLS sintering manufacturing is a new method who permits to realize in the same day the dental crowns with the first control.Powders of Co-Cr alloys presents good sintered properties, good mechanical properties and the sintered probes don’t present tensile strength in the material after DMLS process.

Abstract: Small Intestinal Submucosa (SIS) is a material used from ancient times in foods, and more recently as a biomaterial. To ensure antibacterial properties, the presence of ionic Ag⁺ is benefic and brings a minimum of toxicity to the SIS. In this paper, the electrochemical oxidation of Ag is considered to obtain the ionic Ag⁺. The simultaneous use of Surface Plasmon Resonance (SPR) and Electrochemical techniques opens an insight on Ag oxidation. The study is undertaken in a Simulated Body Fluid (SBF) with ions concentration that closely resembles the concentrations of the human blood plasma for a simulation of the Ag⁺ ions behavior in physiological conditions. The simultaneous SPR and Electrochemical approach highlighted aspects of the ion adsorption into the SIS membrane.

Abstract: In this study, the influence of employing three different sodium hydroxide (NaOH) pretreatment concentration (1, 3 and 5M) and two cleaning methods (Ultrasonic or Rinse) used in rapid biomimetic coating process on phase composition, function groups, thickness, amount and microstructure of the resulted coating was carried out. Regardless of process parameters, x-ray diffraction and Fourier transform infrared spectroscopy revealed that the all coating mainly comprised octacalcium phosphate and hydroxyapatite as main phases while the microstructure similarly consisted of sharp and interconnected plate-like calcium phosphate (CaP) crystals vertically grown on the surface of titanium. However, the change in sodium hydroxide concentration in pretreatment step and cleaning method influenced the weight change after pretreatment, coating continuity and uniformity, but not the weight change after coating. This could be related to amount of the amorphous alkali gel layer formed during pretreatment step which influenced the rate of coating formation in rapid biomimetic coating process.

Abstract: The influence of sintering temperature on the microwave dielectric properties and microstructure of the (1-y)Nd_0.96Yb_0.04(Mg_0.5Sn_0.5)O₃-yCa_0.8Sr_0.2TiO₃ ceramic system were investigated with a view to their application in microwave devices. The (1-y)Nd_0.96Yb_0.04(Mg_0.5Sn_0.5)O₃-yCa_0.8Sr_0.2TiO₃ ceramic systems were prepared using the conventional solid-state method. The X-ray diffraction patterns of the (1-y)Nd_0.96Yb_0.04(Mg_0.5Sn_0.5)O₃-yCa_0.8Sr_0.2TiO₃ ceramic system shifted to higher angle as y increased. A dielectric constant of 38.2, a quality factor (Q×f) of 53,500 GHz, and a temperature coefficient of resonant frequency of-3 ppm/°Cwere obtained when the 0.4 Nd_0.96Yb_0.04(Mg_0.5Sn_0.5)O₃–0.6Ca_0.8Sr_0.2TiO₃ ceramic system was sintered at 1600 °C for 4h.

Abstract: Titanium dioxide (TiO₂) thin films were prepared by means of electrochemical anodisation or anodic spark deposition (ASD) from thin and flat metallic titanium (Ti) films pre-deposited on high quality quartz substrates by electron beam evaporation. AFM analysis indicates the formation of uniform mesoporous layers and a definite increase about 50% of the film thickness upon anodisation and about 90% upon annealing. Anodised mesoporous TiO₂ films have been characterized by Raman spectroscopy, which indicates the presence of well-defined peaks related to anatase structure. Phase transformation from anatase to rutile was observed after annealing at temperatures up to 900°C for 3h.

Abstract: Diffusion coefficients of methane (CH₄) have been obtained by Molecular Dynamics (MD) simulations combined with Einstein fluid equation. Three polymers were considered, namely polyethylene, polypropylene and poly (cis-1,4-butadiene). All calculations were performed by means of Polymer Builder and Amorphous Cell modules within Materials Studio (Accelrys). The obtained diffusivity results are within the range of published results for similar small molecules. Molecular dynamics simulations proved to be a useful tool for understanding the detailed descriptions and transport mechanisms occurring within the material.

Abstract: CaCO₃ polymorphs are intensively studied due to their importance in the nature and the widespread use in the industry as well. This work is dealing with the crystallization of aragonite from vaterite dispersion during the refluxation at 100°C. The characterization of CaCO₃ polymorphs during vaterite transformation was performed with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray powder diffraction (XRPD). The influence of the different refluxing times on the aragonite crystallization was discussed. The purest aragonite, 70.7(2) wt.%, was synthetized in the sample refluxed for 60 minutes. Prolonged refluxation strongly affected aragonite crystals with gradual transformation into calcite.