Papers by Keyword: Porous Structure

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Authors: D.H. Yoon, Eui Kyun Park, Suk Young Kim, J.M. Lee, H.W. Shin, Hong In Shin
Abstract: To develop a suitable scaffold for tissue-engineered bone regeneration, we compared the efficiency of tissue-engineered bone regeneration according to the porous structure of calcium metaphosphate (CMP) ceramic scaffolds. Each scaffold was prepared with a sponge method and a foam-gel method, respectively. Both scaffolds, having either interconnected trabecular pores formed by the sponge method or fully interconnected globular pores formed by the foam-based technology, were not cytotoxic and elicited neither an immune nor an inflammatory response regardless of geometry and fabrication method. The fully interconnected globular porous scaffold showed more favorable compression strength and facilitated osteogenic repair by favoring cellular attachment and osteogenic differentiation with good osteoconductivity compared to the interconnected trabecular pore structured scaffold. These results suggest that the fully interconnected globular porous structure would be more suitable for both a bone substitute and scaffold for bioactive material-based or cell-based tissue bone regeneration.
Authors: Ban Jong Boonchom, Chesta Ruttanapun, Montree Thongkam, Pachernchaipat Chaiyasith, Somsak Woramongkonchai, Samart Kongteweelert, Naratip Vittayakorn
Abstract: Barium hydrogenphosphate, BaHPO4 was synthesized for the first time through simple and rapid method using BaCO3-H3PO4-NaOH, pH =9.0 at room temperature for 30 min. The studied BaHPO4 decomposed in a single well-defined stage via deprotonated hydrogenphosphate reactions, revealed by TG/DTG and DSC techniques. The calculated wavenumbers based on DSC peak were comparable with FTIR results, which support the breaking bonds of P-OH (HPO42-) in the deprotonated hydrogenphosphate reactions. The thermodynamic functions (ΔH*, ΔG*, and ΔS*) for the deprotonated hydrogenphosphate reactions calculated from DSC data indicate that the deprotonated HPO42- reaction occur a lower-energy pathway and spontaneous process. The FTIR, XRD and SEM data of the studied BaHPO4 and its decomposed product Ba2P2O7 are also reported.
Authors: Cui'e Wen, Yun Cang Li
Abstract: Titanium and some of its alloys have received considerable attention for biomedical applications in recent years due to their excellent biocompatibility, high corrosion resistance and relatively low elastic modulus when compared to other metallic implant materials such as Co-Cr alloys and stainless steels. However, these alloys can still suffer from inadequate biocompatibility; lack of biological fixation and biomechanical mismatch with the properties of bone in vivo. In this study, a new biocompatible Ti alloy, Ti4Ta4Sn, consisting of alpha and beta phases was fabricated and their mechanical properties were investigated. Moreover, the Ti alloy was scaffolded into a porous structure using powder metallurgy with an architecture and elastic modulus mimicking those of cancellous bone. Cell culture results indicated that the new porous Ti alloy scaffold possesses excellent in vitro biocompatibility.
Authors: Xiao Fei Niu, Fu Rong Tu
Abstract: The almost monodisperse cobble-like CeO2 nanostructures with many pores and a diameter of 50-100 nm have been successfully synthesized by a smart hydrothermal route. XRD, SEM, XPS, BET, and in situ DRIFT were employed to characterize the samples. The results showed that the cobble-like CeO2 owned a fluorite cubic structure and there are Ce3+ ions and oxygen vacancies in surface of samples. Its catalytic activity was investigated by selective catalytic reduction of NOx with NH3. The results showed that cobble-like CeO2 nanostructures exhibit excellent catalytic performance, which can be attributed to the much larger surface areas, novel morphology and the best redox behaviour of surface oxygen on the CeO2 surface.
Authors: Ji Yi Luan, Xue Mei Wu, Gui Fu Wu, Dong Wei Shao
Abstract: In this paper, the chars of wood dust, corn straw, rice husk and coal pulverized were obtained at different residual time of various pyrolysis temperature (1173 K, 1273 K and 1373 K) during the process of flash pyrolysis in the drop tube furnace (DTF). In order to obtain the parameters of porous structure which included specific surface area, pore volume and fractal dimension of char, low-temperature nitrogen adsorption method was employed to obtain nitrogen adsorption isotherm of chars sample. For the four chars, the corn straw char had the biggest specific surface area and pore volume, the rice husk in second place, the wood dust in third place, and the pulverized coal char in the last one. By taking Frenkel-Halsey Hil (FHH) method to analyze the fractal character of char surface structure, we found that the fractal dimension of biomass except wood char is higher than those of pulverized coal char.
Authors: Wen Yuan Zhang, Rui Xiang Liu, Jie Yang, Chang Ling Zhou, Xue Ye Sui, Chong Hai Wang
Abstract: In this paper we take advantage of the phosphate film which has a porous structure, by phosphate process on the surface of nickel plated copper conductor so as to improve the bonding force of wire and ceramic layer; Through the study of resistance voltage breakdown after phosphate , phosphate liquid was determined Manganese dihydrogen phosphate for 3g100-1ml, Zinc Nitrate was 8g100-1ml, Sodium Fluoride was 0.45g100-1ml; Optimum temperature was 60°C and the appropriate time was 15min at the temperature of 60°C.
Authors: Mervi Puska, Ari-Pekka Forsback, Antti Yli-Urpo, Jukka Seppälä, Pekka K. Vallittu
Abstract: Acrylic bone cements are used to fix joint replacements to bone. The main substance in acrylic bone cement is biologically inert poly(methylmethacrylate), PMMA. The dense PMMA polymer structure of cement does not allow bone ingrowth into cement. Therefore, the main focus of our studies is to modify acrylic bone cement in order to improve its biological properties e.g., by creating porosity in the cement matrix. The porous structure is in situ created using pore-generating filler (i.e., 20 wt% of an experimental biodegradable polyamide) that is incorporated in acrylic bone cement. The aim of this in vitro study was to investigate the biomineralization of acrylic bone cement modified using an experimental biodegradable polyamide.
Authors: Marco A. Lopez-Heredia, Eric Goyenvalle, Eric Aguado, C. Leroux, M. Dorget, Pierre Layrolle
Abstract: Two porous titanium implants with interconnected pore size of 800 and 1200 m in diameter, were fabricated by a rapid prototyping method. Their dimensions and structure accomplished the expected design with accuracy and reproducibility. The porosity of titanium was around 60%. The compressive strength and Young’s modulus were comparable to those of cortical bone with values around 80 MPa and 2.7 GPa, respectively. The implants were implanted bilaterally in the femoral epiphysis of 12 New Zealand Rabbits. After 3 and 8 weeks, abundant bone formation was found in the titanium porous structure. This work demonstrates that macroporous titanium with controlled shape and porosity is a good candidate for orthopaedic and maxilofacial applications.
Authors: Larysa Ocheretna, David Lukáš
Abstract: Computer simulation of a fluid flow through the declined porous structure is presented in the paper. The hypothesis related to the curious behaviour of the fluid flow inside assembled filters is verified using Lattice Gas Cellular Automata approach. Based on a set of computer simulations the reorganization of the fluid flow inside declined porous structure was obtained for different simulation setups. The results obtained from the computer simulation have shown that LGCA model is not only suitable for a theoretical prediction of a fluid flow inside porous structures but also it can be used as a visualization tool.
Authors: Muhammad Kusumawan Herliansyah, Suyitno, Punto Dewo, Mohd Hamdi Bin Abdul Shukor, A. Ide-Ektessabi
Abstract: The porous Hydroxyapatite (HA) ceramics have found enormous use in biomedical applications including bone tissue regeneration, cell proliferation, and drug delivery. This paper investigates the preparation and characterization of bovine Hydroxyapatite (BHA) porous bone graft by mixing sucrose powder as porogens with bovine bone powder. After uniaxially pressing at 156 MPa and pressurelessly sintering in air atmosphere at 1200°C for 2 hours the bioceramic showed an interconnecting porosity. The XRD analysis indicated that bovine hydroxyapatite (BHA) porous bone graft resulted in this research is single phase HA and is believed to be pure HA as indicated by the peak of the diffraction patterns (JCPDS 9-432). The phase analysis also shows that BHA porous bone graft is highly crystalline with domain crystallites sizes are between ~46 to ~99 nm (~4.6 to ~9.9 Å). Several trace elements in human bone such as titanium (Ti), iron (Fe), nickel (Ni), copper (Cu) and Zinc (Zn) were also detected in BHA porous bone graft as indicated by SR-XRF. This object is promising for bone regeneration because the interconnecting porosity in carbonated apatite provides a good environment for bone attachment and ingrowths
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