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Suitable Material (suitable + material)
Selected AbstractsComparison of cobalt chromium, ceramic and pyrocarbon hemiprostheses in a rabbit model: Ceramic leads to more cartilage damage than cobalt chromiumJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2008Martin Jung Abstract Cartilage wear after hemiarthroplasty remains a problem in orthopedic surgery. The main cause of cartilage wear, apart from incongruency of the joint partners, is generally considered to be the tribology of the material surfaces. This study evaluates in 27 rabbits the degree of cartilage wear of the tibia plateau after hemiarthroplasty with proximal interphalangeal prostheses made of three different materials [cobalt chromium (CoCr), pyrocarbon (PyCa), and ceramic (Cer)]. Three months after hemiarthroplasty, the articulating tibial cartilage was histomorphologically examined and degenerative damage was graded using the modified Mankin score. The mechanical capacity of the cartilage was assessed by stress relaxation testing. The biomechanical properties of the cartilage were significantly superior in the CoCr group as compared with the Cer group (p < 0.03), indicating less damage to the articulating cartilage surface. The Mankin score showed significantly lower values in the CoCr compared with Cer group (p = 0.011), whereas no differences were found between PyCa and CoCr or PyCa and Cer. In contrast to earlier reports, in this hemiarthroplasty model, the CoCr alloy showed less cartilage damage than a ceramic surface. Further, in vivo experiments are necessary to elucidate the controversial issue of the most suitable material for hemiarthroplasty. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source] Deproteinized cancellous bovine bone (Bio-Oss®) as bone substitute for sinus floor elevationJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 3 2003A retrospective, histomorphometrical study of five cases Abstract Objectives: To study in detail the performance of deproteinized cancellous bovine bone (DPBB, Bio-Osso®) granules as a bone substitute, a histomorphometric was performed on five patients treated with DPBB for reconstruction of the severely atrophic maxilla. Material and Methods: DPBB was used as mixture with autogenous bone particles, in concentrations that increased from 20% to 100% DPBB, with the time of healing increasing accordingly from 5 to 8 months. A total of 20 vertical biopsies was taken at the time of fixture installation and used for histomorphometry as undecalcified Goldner stained sections. Results: The results show that in all cases, the DPBB granules had been interconnected by bridges of vital newly formed bone. The volume of bone in the grafted area correlated inversely with the concentration of DPBB grafted, and varied between 37% and 23%. However, the total volume of mineralized material (bone plus DPI3B granules) remained within the same range in all five patients (between 53% and 59%). The high values for osteoid and resorption surface, and the presence of tartrate-resistant acid phosphatase-positive multinucleated osteoclasts in resorption lacunae, indicated that bone remodeling was very active in all grafts. Osteoclasts were also observed in shallow resorption pits on DPBB surfaces. The percentage DPBB surface in contact with bone remained stable at about 35% and could not be related to the proportion of DPBB grafted. Conclusion: Although the number of patients examined was limited, the data suggest that deproteinized cancellous bovine bone, preferably combined with autogenous bone particles, is a suitable material for sinus floor elevation in the severely atrophic human maxilla. Zusammenfassung Ent-Proteinisierter spöngiöser boviner Knochen (Bio-Oss) als Knochenersatz zur Sinusboden-Elevation. Eine retrospektive histomorphometrische Studie an 5 Fällen. Ziele:Um das Verhalten Ent-Proteinisierten spöngiösen bovinen Knochengranulats (DPBB, Bio,Oss) als Knochenersatzmaterial detailliert zu studieren, wurde an 5 Patienten, die mit DPBB zur Rekonstruktion der stark atrophischen Maxilla behandelt wurden, eine histomorphometrische Studie durchgeführt. Material und Methoden:DPBB wurde als Mischung mit autogenen Knochenpartikeln in einer Konzentration von 20 , 100% DPBB verwendet. Die Heilungsdauer wurde entsprechend von 5 auf 8 Monate erhöht. Zum Zeitpunkt der Implantatsetzung wurden insgesamt 20 vertikale Biopsien entnommen und für die Histomorphometrie als nicht-entkalkte, Goldner-gefärbte Schnitte verwendet. Ergebnisse: Die Ergebnisse zeigten in allen Fällen, dass die DPBB-Granula über Brücken von vitalem neu gebildetem Knochen miteinander verbunden waren. Das Volumen des Knochens in dem transplantiertem Gebiet korrelierte umgekehrt mit der Konzentration der transpantierten DPBB und variierte zwischen 37% und 23%. Jedoch lag das Gesamtvolumen des mineralisierten Materials (Knochen+DPBB-Granula)bei allen 5 Patienten im selben Bereich (zwischen 53% und 59%). Die hohen Werte für Ostoid und Resorptionsflächen sowie die Anwesenheit von TRAP-positiven multinukleären Osteoklasten in Resorptionslakunen, zeigte, dass das Knochenremodelling in allen Transplantaten sehr aktiv war. Auch in flachen Resorpionsgrübchen auf der DPBB-Oberfläche wurden Osteoklasten beobachtet. Der Prozentsatz der DPBB-Oberfläche welche im Knochenkontakt war blieb mit etwa 35% stabil und korrelierte nicht mit dem Anteil des transplantierten DPBBs. Schlussfolgerung:Obwohl die untersuchte Patientenzahl sehr gering ist, lassen die Daten vermuten, dass Ent-Proteinisierter spöngiöser boviner Knochen, vorzugsweise mit autogenen Knochenpartikeln kombiniert, ein geeignetes Material für die Sinusboden-Elevation bei stark atrophischer Maxilla ist. Résumé Os bovin spongieux déprotéiné comme substitut osseux dans l'épaississement sinusal. Une étude histomorphométrique rétrospective de cinq cas Le but de cette étude a été d'analyser en détail les performances de l'os bovin spongieux déprotéiné (DPBB, Bio-Oss®) en granules comme substitut osseux par une analyse histomorphométrique effectuée chez cinq patients traités pour une reconstruction au niveau d'un maxillaire sévèrement atrophié. DPBB a été utilisé en mélange avec des particules osseuses autogènes en concentrations augmentaient de 20 à 100% de DPBB, avec un temps de guérison augmentant paralèllement de cinq à huit mois. Vingt biopsies verticales ont ainsi été prélevées au moment du placement des implants et utilisées pour l'histomorphométrie sur coupes colorées Goldner non-décalcifiées. Les résultats ont indiqué que dans tous les cas les granules DPBB ont été interconnectées par des bridges d'os néoformé vivant. Le volume d'os dans l'aire greffée était en corrélation inverse avec les concentrations de DPBB greffées et variait entre 37 et 23 %. Cependant le volume total de matériel minéralisé (os+granules DPBB) restait dans les mêmes moyennes chez les cinq patients (entre 53 et 59 %). Les valeurs importantes pour la surface de résorption et ostéides, et la présence d'ostéoclastes multinucléaires positifs au TRAP dans les lacunes de résorption indiquaient que le remodelage osseux était très actif dans tous les greffons. Les ostéoclastes étaient également observés dans des petites crevasses de résorption étroites sur les surfaces DPBB. Le pourcentage DPBB en contact avec l'os demeurait stable à environ 35% et ne pouvait pas être mis en relation avec la proportion de DPBB greffé. Bien que le nombre de patients examinés aie été très limité, les données suggèrent que l'os bovin spongieux déprotéiné de préférence en combinaison avec des particules d'os autogène est un bon matériel pour l'épaississement du plancher sinusal en présence de maxillaire humain sévèrement atrophié. [source] Assessing the taxonomic status of dingoes Canis familiaris dingo for conservationMAMMAL REVIEW, Issue 2 2006AMANDA E. ELLEDGE ABSTRACT 1The conservation status of the dingo Canis familiaris dingo is threatened by hybridization with the domestic dog C. familiaris familiaris. A practical method that can estimate the different levels of hybridization in the field is urgently required so that animals below a specific threshold of dingo ancestry (e.g. 1/4 or 1/2 dingoes) can reliably be identified and removed from dingo populations. 2Skull morphology has been traditionally used to assess dingo purity, but this method does not discriminate between the different levels of dingo ancestry in hybrids. Furthermore, measurements can only be reliably taken from the skulls of dead animals. 3Methods based on the analysis of variation in DNA are able to discriminate between the different levels of hybridization, but the validity of this method has been questioned because the materials currently used as a reference for dingoes are from captive animals of unproven genetic purity. The use of pre-European materials would improve the accuracy of this method, but suitable material has not been found in sufficient quantity to develop a reliable reference population. Furthermore, current methods based on DNA are impractical for the field-based discrimination of hybrids because samples require laboratory analysis. 4Coat colour has also been used to estimate the extent of hybridization and is possibly the most practical method to apply in the field. However, this method may not be as powerful as genetic or morphological analyses because some hybrids (e.g. Australian cattle dog × dingo) are similar to dingoes in coat colour and body form. This problem may be alleviated by using additional visual characteristics such as the presence/absence of ticking and white markings. [source] Elastic constants of aluminum nitridePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2007M. Kazan Abstract We report on the application of Brillouin spectroscopy as an approach to non-destructive optical characterization of the elastic constants of semiconductors with the wurtzite symmetry. Three different configurations were used to achieve a complete determination of the elastic stiffness constants of bulk AlN substrates grown by the Physical Vapor Transport (PVT) method. The scattering diagrams of these three configurations are presented showing the geometrical arrangements necessary to observe all the elastic stiffness constants for the partially nontransparent wurtzite type of the crystal structure. Because aluminum nitride (AlN) is a suitable material for the fabrication of light emitting devices, the characterization of its elastic constants was carried out very precisely to provide a reliable data which can be used for the determination of residual stress arising during the growth of AlN thin films or wide band gap semiconductor thin films on substrates of AlN. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Design of an energy conversion system with decomposition of H2O and CO2 using ferritesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2004H. C. Shin Abstract The energy conversion system was designed in order to reduce the green-house effect and to get energy resources by decomposition of CO2 and H2O. This system is consisted of two parts, one is CO2 decomposition with the reduced ferrite by H2 and the other is H2O decomposition with reduced ferrite by CH4. CH4 could be synthesized in this system by methanation reaction using carbon, which was deposited on the ferrite surface in the CO2 decomposition process. Also, CH4 was used as reducing gas to reduce the ferrite for H2O decomposition. H2O was decomposed by oxidation of oxygen-deficient ferrite. In this energy conversion system, the reduced Cu-ferrite easily decomposed CO2 and H2O into the useful gases such as CO and H2, respectively. Cu-ferrite is a suitable material to apply to this system because it showed excellent redox reactivity on the energy conversions. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis, characterization, and thermal properties of phosphorylated chitin for biomedical applicationsPOLYMER ENGINEERING & SCIENCE, Issue 5 2009R. Jayakumar The present study investigates a suitable material, which is expected to have biocompatibility and to promote tissue regeneration. For this purpose, we have chosen chitin that was chemically modified by phosphorylation with high degree of substitution. The phosphorylated chitin (P-chitin) was synthesized using the H3PO4/P2O5/ET3PO4/hexanol method. The structure of P-chitin was analyzed by FTIR, 31P- and 13C-NMR spectroscopic studies, scanning electron microscopy, and X-ray diffraction. The thermal properties of the P-chitin were also characterized by thermogravimetric analyses. The highly phosphorylated chitin derivatives prepared by this method were soluble in water and amorphous in nature. Thus, H3PO4/P2O5/ET3PO4/hexanol method provides a versatile and alternative route for synthesis of P-chitin, which would be useful for biomedical applications. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source] Fundamentplatten aus Stahlbeton und Stahlfaserbeton.BETON- UND STAHLBETONBAU, Issue 9 2006Experimentelle Untersuchungen zur Gebrauchstauglichkeit und Tragfähigkeit Ein- und Mehrfamilienhäuser werden zunehmend statt auf Streifenfundamenten auf Fundamentplatten gegründet. Vorteile ergeben sich neben der wirtschaftlicheren Ausführung der Aushubarbeiten durch die einfachere Herstellung der Platte. Bei der Ausführung als Stahlfaserbetonplatte ergeben sich besonders wirtschaftliche Lösungen dann, wenn an die Gebrauchstauglichkeit keine besonderen Anforderungen wie Wasserdichtheit oder Rißbreitenbeschränkung gestellt werden. An der Fachhochschule Aachen wurden vergleichende experimentelle Untersuchungen an Bodenplatten aus Beton, Stahlbeton und Stahlfaserbeton unter Lastbeanspruchung durchgeführt. Es konnte nachgewiesen werden, daß Stahlfaserbeton für Fundamentplatten ein geeigneter Werkstoff ist, wenn Mindestanforderungen an die Steifigkeit des Bodens eingehalten werden. Bei erhöhten Anforderungen an die Gebrauchstauglichkeit werden Stahlbeton oder Kombinationen aus Stahlfaserbeton und Stahlbeton als sinnvoll erachtet, wenn diese auf Basis einer elastischen Schnittgrößenermittlung bemessen werden. Reinforced Concrete and Steel Fibre Reinforced Concrete Rafts Experimental tests on serviceability and ultimate loading performance Houses and residential buildings are increasingly built on rafts instead of strip foundations. The main advantages of rafts are more efficient excavation works and easy concreting of the rafts itself. The use of steel fibre reinforced concrete slabs offers economic advantages if there are no special requirements on service ability such as water tightness or crack limitations. At Aachen University of Applied Sciences a comparative experimental study on the load carrying behaviour of rafts made of concrete, reinforced concrete and steel fibre reinforced concrete was carried out. The tests have proven steel fibre concrete as suitable material for rafts in case of sufficient stiffness of the subbase. In case of special requirements on service ability, reinforced concrete or combined fibre and bar reinforced concrete should be used. In that case stresses should be calculated based on the elastic theory. [source] Potential of agroindustrial waste from olive oil industry for fuel ethanol productionBIOTECHNOLOGY JOURNAL, Issue 12 2007Tania I. Georgieva Abstract Olive pulp (OP) is a highly polluting semi-solid residue generated from the two-stage extraction processing of olives and is a major environmental issue in Southern Europe, where 80% of the world olive oil is produced. At present, OP is either discarded to the environment or combusted with low calorific value. In this work, utilization of OP as a potential substrate for production of bioethanol was studied. Enzymatic hydrolysis and subsequent glucose fermentation by baker's yeast were evaluated for OP from 10% to 30% dry matter (i.e., undiluted). Enzymatic hydrolysis resulted in an increase in glucose concentration by 75%, giving final glucose yields near 70%. Fermentation of undiluted OP hydrolysate (OPH) resulted in the maximum ethanol produced (11.2 g/L) with productivity of 2.1 g/L/h. Ethanol yields were similar for all tested OPH concentrations and were in the range of 0.49-0.51 g/g. Results showed that yeast could effectively ferment OPH even without nutrient addition, revealing the tolerance of yeast to OP toxicity. Because of low xylan (12.4%) and glucan (16%) content in OP, this specific type of OP is not a suitable material for producing only ethanol and thus, bioethanol production should be integrated with production of other value-added products. [source] Neurite Outgrowth on Nanocomposite Scaffolds Synthesized from PLGA and Carboxylated Carbon Nanotubes,ADVANCED ENGINEERING MATERIALS, Issue 12 2009Hyun Jung Lee Abstract Carbon nanotubes (CNTs) have been suggested as suitable materials for biomedical applications, especially in the neural area. It is essential not only to investigate the biocompatibility of CNTs with the neural system but also to determine proper methods for applying CNTs to neuronal growth. This work represents the first application of CNTs by electrospun poly(D,L -lactic-co-glycolic acid) (PLGA) scaffolds for a neural system. We synthesized electrospun nanocomposites of PLGA and single-walled carbon nanotubes functionalized by carboxylic acid groups (c- SWNTs), and investigated neurite outgrowth from SH-SY5Y cells on these nanocomposites as compared to that on fibrous PLGA alone. Cells on our PLGA/c -SWNT nanocomposite showed significantly enhanced mitochondrial function and neurite outgrowth compared to cells on PLGA alone. We concluded that c -SWNTs incorporated into fibrous PLGA scaffolds exerted a positive role on the health of neural cells. [source] Growth of osteoblast-like cells on biomimetic apatite-coated chitosan scaffoldsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2008I. Manjubala Abstract Porous scaffold materials that can provide a framework for the cells to adhere, proliferate, and create extracellular matrix are considered to be suitable materials for bone regeneration. Interconnected porous chitosan scaffolds were prepared by freeze-drying method, and were mineralized by calcium and phosphate solution by double-diffusion method to form nanoapatite in chitosan matrix. The mineralized chitosan scaffold contains hydroxyapatite nanocrystals on the surface and also within the pore channels of the scaffold. To assess the effect of apatite and porosity of the scaffolds on cells, human osteoblast (SaOS-2) cells were cultured on unmineralized and mineralized chitosan scaffolds. The cell growth on the mineralized scaffolds and on the pure chitosan scaffold shows a similar growth trend. The total protein content and alkaline phosphatase enzyme activity of the cells grown on scaffolds were quantified, and were found to increase over time in mineralized scaffold after 1 and 3 weeks of culture. The electron microscopy of the cell-seeded scaffolds showed that most of the outer macropores became sealed off by a continuous layer of cells. The cells spanned around the pore wall and formed extra cellular matrix, consisting mainly of collagen in mineralized scaffolds. The hydroxyproline content also confirmed the formation of the collagen matrix by cells in mineralized scaffolds. This study demonstrated that the presence of apatite nanocrystals in chitosan scaffolds does not significantly influence the growth of cells, but does induce the formation of extracellular matrix and therefore has the potential to serve for bone tissue engineering. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source] Using carbon isotopes to track dietary change in modern, historical, and ancient primatesAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2009Matt Sponheimer Abstract Stable isotope analysis can be used to document dietary changes within the lifetimes of individuals and may prove useful for investigating fallback food consumption in modern, historical, and ancient primates. Feces, hair, and enamel are all suitable materials for such analysis, and each has its own benefits and limitations. Feces provide highly resolved temporal dietary data, but are generally limited to providing dietary information about modern individuals and require labor-intensive sample collection and analysis. Hair provides less well-resolved data, but has the advantage that one or a few hair strands can provide evidence of dietary change over months or years. Hair is also available in museum collections, making it possible to investigate the diets of historical specimens. Enamel provides the poorest temporal resolution of these materials, but is often preserved for millions of years, allowing examination of dietary change in deep time. We briefly discuss the use of carbon isotope data as it pertains to recent thinking about fallback food consumption in ancient hominins and suggest that we may need to rethink the functional significance of the australopith masticatory package. Am J Phys Anthropol 140:661,670, 2009. © 2009 Wiley-Liss, Inc. [source] The case for MR-compatible robotics: a review of the state of the artTHE INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY, Issue 2 2008Haytham Elhawary Abstract Background The numerous imaging capabilities of magnetic resonance imaging (MRI) coupled with its lack of ionizing radiation has made it a desirable modality for real-time guidance of interventional procedures. The combination of these abilities with the advantages granted by robotic systems to perform accurate and precise positioning of tools has driven the recent development of MR-compatible interventional and assistive devices. Methods The challenges in this field are presented, including the selection of suitable materials, actuators and sensors in the intense magnetic fields of the MR environment. Results Only a small number of developed systems have made it to the clinical level (only two have become commercial ventures), showing that the field has not yet reached maturity. Conclusions A brief overview of the current state of the art is given, along with a description of the main opportunities, possibilities and challenges that the future will bring to this exciting and promising field. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||||||||