We present a systematic study on the preparation, characteration and potential application of Fe3O4 and Fe3O4@SiO2 nanoparticles. Fe3O4 nanoparticles of controllable diameters were successfully synthesized by solvothermal system with tuning pH. The magnetic properties of nanoparticles were measured by vibration sample magnetometer. Fe3O4@ SiO2 nanoparticles were obtained via classic Stöber process. Streptavidin coated Fe3O4@SiO2 nanoparticles were prepared by covalent interaction. The quantity of streptavidin bound to nanoparticles was determined by UV-Vis spectrometer. To evaluate the binding efficiency and capacity of nucleic acid on nanoparticles, the capture of biotinylated oligonucleotide on streptavidin coated Fe3O4@SiO2 nanoparticles at different concentration was estimated by fluorescence detection. Both Fe3O4 and Fe3O4@SiO2 nanoparticles exhibited well crystallization and magnetic properties. The maximal amount of streptavidin immobilized onto the Fe3O4@SiO2 nanoparticles was 29.3 microg/mg. The saturation ratio of biotinylated oligonucleotides captured on streptavidin coated Fe3O4@SiO2 nanoparticles was 5 microM/mg within 20 minutes, indicating that FeO4@SiO2 nanoparticles immobilized by streptavidin were excellent carriers in nucleic acid analysis due to their convenient magnetic-separation property. Therefore, the synthesized Fe3O4 and Fe3O4@SiO2 nanoparticles with controllable size and high magnetic saturation have shown great application potentials in nucleic acid research.
The thickener structure of polyurea grease has a crucial effect on its properties. Therefore, it is very important to study the relationship between a thickener structure and physical and performance properties. In this study, polyurea greases were synthesised, having a different number of urea groups in per polyurea thickener molecule. Properties such as dropping point, penetration, oil separation, shear stability and four-ball wear and extreme pressure (EP) were evaluated. The result shows that properties of polyurea grease vary with the number of urea group per polyurea molecule. Based on molecular theory, the mechanisms explaining these effects are briefly discussed.
For a River-Sea ship hull with a relatively low torsional rigidity due to the large deck openings, the analysis of the effect of torsion induced warping stress[1] on the structural strength as well as the ultimate hull strength interaction relationships between the torsion and vertical bending is of significant importance. The present study deals with the ultimate strength of a River-Sea ship under combined action of bending and torsion by the means of numerical and experimental research.
Based on the results, a proposed equation defining the ultimate strength interaction relationship for this River-Sea ship is given.
In this paper, a new simplified finite element model is proposed for ship-jacket platform collision. This model can achieve all kinds of concerned parameters and time history curves through once calculation. This paper also discusses the effect of stain rate in ship-platform collision. On the basis of the above work, finite element numerical simulation of ship-platform collision is carried out. Some important results such as collision forces, stress, local deformations, distribution of various energies and displacement of platform are discussed. At last, some useful conclusions are achieved.
Abstract. Based on the several practical research on real ship hull ultimate strength model test, a design method of hull structure model for ultimate strength test, which combine the numerical simulation analysis with a similar model design are proposed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.