Advanced Materials Research Vols. 311-313

Abstract: Defect in surface induction hardening layer at the eccentric axle neck of C38N2 automobile engine crankshaft was investigated. Fracture morphology and microstructure of the defect were analyzed by optical microscope and scanning electron microscope, and compared with the microstructure characteristics in defect-free locations. And the reasons and the technical procedures of the defects were discussed. The results indicated that the surface defect is a quenching crack caused by induction hardening process. The crack propagation is along prior-austenite grain boundaries and is affected by MnS inclusions. Martensite lath in surface hardening layer at position having 45° or 90° with mouldjoint is shorter than that at the defect position. Distribution characteristics of inclusions at different positions have significant difference. Inclusions in the defect position are slender spindle and are distributed nearly vertical the crankshaft surface. Distribution of the inclusions in the 45° position is approximately parallel to the crankshaft surface. And the inclusions in the 90° position are mostly graininess. Distributional difference of the inclusions at the different positions is related to uneven flowing of metal during stamp forging process.

Abstract: The thermal properties and rheological behavior of concentrated regenerated silk fibroin aqueous solution from 15% to 37% was investigated by differential scanning calorimetry (DSC) and rheometer. Also the conformation of solutions was characterized by Raman spectra. It was discovered that the major endothermic peak in the DSC curves shifted toward the lower temperature region with increasing the concentration. This behavior suggests increasing the concentration can accelerate conformational transition of silk fibroin from random coil and α-helix to β-sheet structure. In addition, it was found that the viscosity of solution increased with increasing concentration in favor of spinning.

Abstract: To improve the adaptability of small underwater vehicle for different requirements in various work, it propose a innovative design scheme to provide a reconfigurable structure for underwater vehicle. By analyzing the current structure of modern modular underwater vehicles and considering the future application requirements of small underwater vehicle, it partition independent standard module for each functional unit and design the mechanical and electrical interface for the connection of those modules. Furthermore, it gives some feasible reconfigurable structure of the modular underwater vehicle to meet the typical application requirements.

Abstract: Several biomaterials have been widely used in the treatment of cancer. However, how these biomaterials alter gene expression is poorly understood. The problem of identifying genes that are differentially expressed across varying biological conditions or in response to different biomaterials based on microarray data is a typical multiple testing problem. In this paper, we focus on FDR control for large-scale multiple testing problems, by our proposed statistics and resampling method, a powerful FDR controlling procedure for large-scale multiple testing problems is provided. Simulations show that, our Fiducial estimator is accurate and stable than other five traditional methods, with satisfactory FDR control. In particular, we propose a generally applicable estimate of the proposed procedure for identifying differentially expressed genes in microarray experiments. This microarray method consistently shows favorable performance over the existing methods. For example, in testing for differential expression between two breast cancer tumor types, the proposed procedure provides increases from 37% to 127% in the number of genes called significant at a false discovery rate of 3%.

Abstract: One new type metastable β-titanium-alloy for biomedical applications Ti-25Nb-2Mo-4Zr (wt %) with lower elastic modulus was designed based on the d-electron alloy design method and prepared in this study. The microstructure and basic mechanical properties of designed alloy were investigated in this paper. The test results show that the Yang’s modulus is 65GPa and the tensile strength is 863MPa of designed alloy after solution treatment at 700°C for 0.5 h; the Yang’s modulus is 68GPa and the tensile strength is 1032MPa for the designed alloy after aging treatment at 500°C for 2 h. The designed alloy with lower Yang’s modulus is expected to have good prospects for implant biomaterials for its excellent biomechanical compatibility.

Abstract: As a new and innovative cutting method, abrasive water jet cutting has gained more and more attention from all around the world. During the cutting or machining process, the energy consumption is one of the key factors affecting the overall cutting quality. An energy conservation study was performed in this paper and the energy-related models were also described here.

Abstract: To correct error in theoretical model of process-stress accelerated test, a new calculation method is proposed. The new method, based on computer-aided calculation, can significantly reduce the error of the model. Theoretical data is calculated using both the new model algorithm, which is the root test method, and the old model algorithm. The results show that the old model algorithm can generate error more than 13% in the activation energy and error more than 150% in the extrapolated lifetime (Q≤1.0eV), while the new model algorithm generates error less than 1% in activation energy, and error less than 4.1% in the extrapolated lifetime.

Abstract: Hydroxyapatite (HAP) urchins were synthesized by a facile hydrothermal method using calcium nitrate, ammonium dihydrogen phosphate, diamine tetraacetic acid disodium salt as complexing agent and ethonalamine as alkaline source. The influence of hydrothermal time on crystallinity and morphology of HAP have been investigated. The results indicate that well-crystallized HAP urchins can be synthesized at 180°C for 24h. SEM images show a large area of urchin-like microspheres consisted of a number of ribbons with lengths ranging from 2 to 5μm. Based on XRD and SEM results, the formation mechanism of HAP crystals has been discussed. A typical anti-inflammatory drug, ibuprofen, was used for drug loading, and the release behaviors of ibuprofen in a simulated body fluid (SBF) were studied. The results indicate that HAP urchins showed a favorable sustained release property for ibuprofen.

Abstract: Bone is an anisotropic inhomogeneous material, and its piezoelectric behavior is more complex than mineral piezoelectric materials such as quartz crystal or ceramics. This article aimed to understand the piezoelectric properties of bone by investigating its converse piezoelectric effect. Bending deformation of bone specimens subjected to an external electric field was observed. Displacements or deflections of bone cantilever beams were measured by a high resolution digital microscope combined with digital image correlation technique. In order to demonstrate the validity of the experiment, specimens made of non piezoelectric materials were also tested in the same experimental condition as bone. The results indicate that the bending deformation of the bone cantilever may come from the non uniform piezoelectric properties of bone, compared to an analytical solution.

Abstract: In the study, uniform design method is used to define the mix proportion of resin concrete. According to results obtained from the experiment, the optimal mix proportion of resin concrete can be got through regression analysis by using SPSS software, and MATLAB software together. The methods not only reduce the number of tests and the test costs greatly, but also provide an accurate and reliable design concept for the application of resin concrete in practical engineering.