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91.
This study examines the surface morphology, microstructure, and chemical composition of titanium surfaces treated by anodic spark oxidation in phosphate buffer solution at pH 2, 7 and 12. The pH of the electrolyte was found to play a substantial role in the formation of different morphologies, chemical compositions, and pore dimensions with microporous structures. SEM revealed variation in the topologies of the anodized surface with electrolyte pH. Porous structures with uniform pores and high roughness were obtained in pH 12 solutions. However, intense anatase crystal was obtained at pH 7. The relationship between surface characteristics of titanium and initial interactions of titanium-osteoblasts was also in vestigated. Our findings demonstrated the cell viability and proliferation on the anodic oxides produced at pH 12 to be superior to those produced at pH 2 and 7 as well as on the control titanium surface. This study also provides evidence of enhanced osteoblast adhesion on anodized metal substrates under in vitro conditions.  相似文献   
92.
The effect of Fe3+ concentration on saturation magnetic flux density (Bs) of electrodeposited Co40-44Fe60-56 films was investigated. The results show that if the conditions at the electrochemical interface for nucleation/precipitation of iron(III) hydroxide (Fe(OH)3) are reached, the Bs of electrodeposited Co40-44Fe60-56 films quickly decreases as a result of the Fe(OH)3 incorporation into deposit. These conditions are discussed as a function of the solution formulation (pH) and the parameters of electrodeposition process (current density, current efficiency, diffusion layer thickness) and a simple analytical model is developed qualitatively describing the hydroxide incorporation phenomenon and resulting decrease in Bs of Co40-44Fe60-56 films.  相似文献   
93.
94.
A tapered coaxial tip in a parallel plate waveguide is investigated. A boundary-value problem of electromagnetic scattering from a tapered coaxial monopole is solved rigorously based on the Fourier transform, eigenfunction expansion, and mode matching. Scattering parameters are represented in a series and computed to understand the behavior of the scattering in terms of the coaxial tip geometry.  相似文献   
95.
The effect of forward and reverse electrostatic discharge (ESD) on the electro‐optical characteristics of oxide vertical‐cavity surface‐emitting lasers is investigated using a human body model for the purpose of understanding degradation behavior. Forward ESD‐induced degradation is complicated, showing three degradation phases depending on ESD voltage, while reverse ESD‐induced degradation is relatively simple, exhibiting two phases of degradation divided by a sudden distinctive change in electro‐optical characteristics. We demonstrate that the increase in the threshold current is mainly due to the increase in leakage current, nonradiative recombination current, and optical loss. The decrease in the slope efficiency is mainly due to the increase in optical loss.  相似文献   
96.
Metallurgical and Materials Transactions B - A thermodynamic equilibrium model is developed for the distribution of nickel between two phases for the system nickel sulfate-acetate...  相似文献   
97.
Accurate prediction of fatigue failure times of materials such as fracture and plastic deformation at various stress ranges has a strong bearing on practical fatigue design of materials. In this study, we propose a novel genetic‐based iterative quantile regression (GA‐IQR) algorithm for analyzing fatigue curves that represent a nonlinear relationship between a given stress amplitude and fatigue life. We reduce the problem to a linear framework and develop the iterative algorithm for determining the model coefficients including unknown fatigue limits. The procedure keeps updating the estimates in a direction to reduce its resulting error. Also, our approach benefits from the population‐based stochastic search of the genetic algorithms so that the algorithm becomes less sensitive to its initialization. Compared with conventional approaches, the proposed GA‐IQR requires fewer assumptions to develop fatigue model, capable of exploring the data structure in a relatively flexible manner. All procedures and calculations are quite straightforward, such that the proposed quantile regression model has a high potential value in a wide range of applications for exploring nonlinear relationships with lifetime data. Computational results for real data sets found in the literature present good evidences to support the argument. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
98.
The corrosion behaviour and change of the phase fraction in welded 24Cr Duplex stainless steel was investigated for different chemical composition ranges of Mo contents. Filler metal was produced by fixing the contents of Cr, Ni, N, and Mn while adjusting the Mo content to 0.5, 1.4, 2.5, 3.5 wt%. The δ-ferrite fraction was observed to increase as the content of Mo increased. A polarisation test conducted in a salt solution, indicated the pitting corrosion potential increased continuously to 3.5 wt% Mo, while the corrosion potential changed most between 0.5 and 1.41 wt% Mo. The location of the pitting corrosion in 0.5 wt% Mo steel was randomly distributed, but it occurred selectively at the grain boundary between the γ- and δ-ferrite phases in 1.4, 2.5 and 3.5 wt% Mo steel. Energy dispersive X-ray spectroscopy mapping analysis showed that areas deficient in Cr, Mo, and Ni occurred around the grain boundary of the γ- and δ-ferrite phases. Non-metallic inclusions are thought to act as initiation points for the pitting corrosion that occurs in the salt solution initially as a result of the potential difference between the matrix structure and the incoherent inclusions.  相似文献   
99.
100.
Marine organisms are rich sources of new, biologically active compounds. Seaweeds have traditionally been used as food, but have also been used as folk medicine, particularly by coastal peoples. Recently, much attention has been paid to the anticancer activity of seaweed. Thus, we have screened organic extracts of seaweeds for their anticancer activity against human cell lines, and selected Corallina pilulifera as a candidate for use in treatment. The ethanolic extracts of Corallina pilulifera (EECP) showed cytotoxic activity against human cervical adenocarcinoma cell line, HeLa. The IC50 of EECP against the HeLa cells was 250 μg/ml. Treatment of HeLa cells with various concentrations of EECP resulted in growth inhibition and induction of apoptosis in a dose-dependent manner. In Western blot analysis, apoptosis in the HeLa cells was associated with the release of cytochrome C from mitochondria into the cytosol, activation of caspase-3 and caspase-8, and proteolytic cleavage of PARP (poly (ADP-ribose) polymerase). These results strongly suggest that EECP may be a potential candidate in the field of anticancer drug discovery.  相似文献   
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