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991.
A. W. Wren A. Coughlan F. R. Laffir M. R. Towler 《Journal of materials science. Materials in medicine》2013,24(2):271-280
Glass polyalkenoate cements (GPCs) have previously been considered for orthopedic applications. A Zn–GPC (BT 101) was compared to commercial GPCs (Fuji IX and Ketac Molar) which have a setting chemistry analogous to BT 101. Handling properties (working, T w and setting, T s times) for BT 101 were shorter than the commercial GPCs. BT 101 also had a higher setting exotherm (S x —34 °C) than the commercial GPCs (29 °C). The maximum strengths for BT 101, Fuji IX, and Ketac Molar were 75, 238, and 216 MPa (compressive, σ c), and 34, 54, and 62 MPa (biaxial flexural strengths, σ f), respectively. The strengths of BT 101 are more suitable for spinal applications than commercial GPCs. 相似文献
992.
A. W. Wren J. P. Hansen S. Hayakawa M. R. Towler 《Journal of materials science. Materials in medicine》2013,24(5):1167-1178
Glass polyalkenoate cements (GPCs) have exhibited potential as bone cements. This study investigates the effect of substituting TiO2 for SiO2 in the glass phase and the subsequent effect on cement rheology, mechanical properties, ion release and antibacterial properties. Glass characterization revealed a reduction in glass transition temperature (T g ) from 685 to 669 °C with the addition of 6 mol % TiO2 (AT-2). Magic angle spinning nuclear magnetic resonance (MAS-NMR) revealed a shift from ?81 ppm to ?76pmm when comparing a Control glass to AT-2, indicating de-polymerization of the Si network. The incorporation of TiO2 also increased the working time (T w ) from 19 to 61 s and setting time (T s ) from 70 to 427 s. The maximum compressive strength (σ c ) increased from 64 to 85 MPa. Ion release studies determined that the addition of Ti to the glass reduced the release of zinc, calcium and strontium ions, with low concentrations of titanium being released. Antibacterial testing in E. coli resulted in greater bactericidal effects when tested in aqueous broth for both titanium containing cements. 相似文献
993.
AbstractThe results of an experimental study on clear-water scour at long skewed rectangular piers under steady flows at threshold velocity are presented. The scour mechanisms due to skewness effects with a wide range of angle of attack, α, and two sizes of uniform cohesionless bed sediment (d50 = 0.23 and d50 = 0.80 mm) have been investigated in a 50-m-long, 1.5-m-wide, and 2.0-m-deep flume. Empirical relation to demonstrate the effects of skewness in terms of dimensionless variables, such as aspect ratio (L/b), the angle of attack (α), flow shallowness (y/Bα), sediment coarseness (Bα/d50), the sediment gradation coefficient (σg), on scour depth is presented. The empirical relation is focused on predicting the angle of attack factor, Kα. The experimental data obtained in this study and data available from the literature were used to validate the predictions of existing methods and the accuracy of the proposed method. The proposed method gives reasonable scour depth predictions and was verified with statistical methods where the mean error was reduced from 53.6 to 18.1%. 相似文献
994.
AbstractThe investigation of twin-propeller jets as ships undergo acceleration is essential. This form of jet has been triggering problematic consequences such as seabed scouring. In order to prevent such scouring, near-bed velocities must first be analyzed in order to design the necessary protection when the under keel clearance of a ship is low when it is near port structures. This paper presents experimental work performed by Laser Doppler Anemometry. It is noticed that research into twin-propeller jet profiles still remains limited in the literature. Therefore, we intend to analyze twin-propeller axial velocity profiles and look into several flow characteristics such as efflux velocity and its decay pattern. Also, the measured velocity profile is compared to that of a single-propeller jet. Current results show that scouring is more severe in the case of the twin-propeller jets. 相似文献
995.
In this research, the properties of lightweight geopolymer concrete containing aggregate from recycle lightweight block were studied. The recycle block was crushed and classified as fine, medium and coarse aggregates. The compressive strength and density with various liquid alkaline/ash ratios, sodium silicate/NaOH ratios, NaOH concentrations, aggregate/ash ratios and curing temperatures were tested. In addition, porosity, water absorption, and modulus of elasticity were determined. Results showed that the lightweight geopolymer blocks with satisfactory strength and density could be made. The 28-day compressive strength of 1.0–16.0 MPa, density of 860–1400 kg/m3, water absorption of 10–31% and porosity of 12–34%, and modulus of elasticity of 2.9–9.9 GPa were obtained. It can be used as lightweight geopolymer concrete for wall and partition. 相似文献
996.
Halimahtun M. Khalid Anders Opperud Jenthi Krishna Radha Qianli Xu Martin G. Helander 《Theoretical Issues in Ergonomics Science》2013,14(3):318-334
This article describes a methodology for elicitation and analysis of affective needs for vehicle design. Driven by the concept of citarasa or emotional intent, the method has five steps. First, a model of emotional intent was conceptualised; second, a semantic framework of citarasa words was developed that mapped words to specific vehicle components to form a citarasa ontology; third, customer citarasa were elicited in the field using probe interview technique; fourth, affective needs were refined through Web survey; and fifth, the elicited citarasa were analysed using data mining techniques and the citarasa analysis tool. The tool is linked to the citarasa database that enables analysis of affective needs in several countries in Europe and Asia. The system has been technically verified, validated and tested for usability with consumers and automotive end-users. 相似文献
997.
AbstractOsteoarthritis-oriented synovial fluid (OASF), i.e., that typical of a patient with osteoarthritis, has different physical and biological characteristics than bovine serum (BS), a lubricant widely used in biotribological investigations. Micro-dimpled and diamond-like carbon- (DLC) coated surfaces are key emerging interfaces for orthopedic implants. In this study, tribological performances of dimpled surfaces, with and without DLC coating, have been investigated under both BS and OASF. The friction tests were performed utilizing a pin on a disk tribometer, whereas contact pressure, speed, and temperature were simulated to a ‘medium walking gait’ of hip joint conditions. The mechanical properties of the specimen and the physical properties of the lubricant were characterized before the friction test. Raman analysis was conducted to identify the coating condition both before and after the test. The DLC-coated dimpled surface showed maximum hardness and residual stress. A DLC-coated dimpled surface under an OASF lubricated condition yielded a lower friction coefficient and wear compared to those of plain and dimpled specimens. The higher graphitization of coated materials with increasing load was confirmed by Raman spectroscopy. 相似文献
998.
Shahira Liza Junko Hieda Hiroki Akasaka Naoto Ohtake Yusuke Tsutsumi Akiko Nagai 《Science and Technology of Advanced Materials》2013,14(1):76-87
AbstractDiamond-like carbon (DLC) material is used in blood contacting devices as the surface coating material because of the antithrombogenicity behavior which helps to inhibit platelet adhesion and activation. In this study, DLC films were doped with boron during pulsed plasma chemical vapor deposition (CVD) to improve the blood compatibility. The ratio of boron to carbon (B/C) was varied from 0 to 0.4 in the film by adjusting the flow rate of trimethylboron and acetylene. Tribological tests indicated that boron doping with a low B/C ratio of 0.03 is beneficial for reducing friction (μ = 0.1), lowering hardness and slightly increasing wear rate compared to undoped DLC films. The B/C ratio in the film of 0.03 and 0.4 exhibited highly hydrophilic surface owing to their high wettability and high surface energy. An in vitro platelet adhesion experiment was conducted to compare the blood compatibility of TiNb substrates before and after coating with undoped and boron doped DLC. Films with highly hydrophilic surface enhanced the blood compatibility of TiNb, and the best results were obtained for DLC with the B/C ratio of 0.03. Boron doped DLC films are promising surface coatings for blood contacting devices. 相似文献
999.
Sondra Walha Houcine Naïli Samia Yahyaoui Basem Fares Ali Mark M. Turnbull Tahar Mhiri Seik Weng Ng 《Journal of Superconductivity and Novel Magnetism》2013,26(2):437-442
A single crystal structure determination of the complex (C5H9N3)CuCl4 [henceforth I] has been carried out. It crystallizes in the orthorhombic space group Cmca, with the cell parameters a=6.7053(5) Å, b=22.4171(19) Å, c=13.4173(9) Å, V=2016.8(3) Å3, and Z=8. In the complex, the anion is comprised of infinite zigzag chains of monochloro-bridged $\mathrm{CuCl}_{4}^{2-}$ units ?–CuCl3–μ–Cl–CuCl3–μ–Cl–CuCl3–? surrounded by the pyridinium-ammonium cations. The Cu ions are five-coordinate to chloride ions in a distorted square-pyramidal geometry with the zigzag chains formed by corner-sharing polyhedra. The Cu ion is located 0.151 Å above the basal plane. In the crystal, there are four intermolecular hydrogen bonding interactions, linking the CuCl chains to the cations to form a 2D-network. The resulting 2D-networks are further linked by aryl?aryl (π?π) interactions within the cationic chains leading to a 3D-network. Variable temperature magnetic susceptibility data were fit to a one-dimensional S=1/2 antiferromagnetic chain model yielding C=0.44(1) emu-K/mol-Oe and J=?37(1) K. 相似文献
1000.
Muhammad Z. Ahmad Vladimir B. Golovko Rohul H. Adnan Faridah Abu Bakar Jan-Yves Ruzicka David P. Anderson Gunther G. Andersson Wojtek Wlodarski 《International Journal of Hydrogen Energy》2013
Controlled amounts of chemically synthesised gold (Au) nanoclusters were deposited onto tungsten trioxide (WO3) nanostructured thin films as sensors for hydrogen. The Au/WO3 thin films were characterised by XPS, XRD, SEM and TEM. Performance of Au/WO3 films was tested at operating temperatures varying from room temperature to 450 °C. It was demonstrated that Au metal loading plays an important role in defining enhancement of the sensor response towards hydrogen. “Less is more” principle applies to the reported here sensors as materials made using lower concentration of Au nanoclusters demonstrated significantly better response. HRTEM images of the Au/WO3 thin films provide evidence that the more active sensors are enriched with smaller Au nanoparticles (≤5 nm). Fast response towards H2 within a wide range of industrially relevant concentrations, excellent baseline stability and signal reproducibility at optimized operating temperature demonstrate feasibility of this novel approach toward fabrication of sensors. 相似文献