Mechanism of Martensitic to Equiaxed Microstructure Evolution during Hot Deformation of a Near-Alpha Ti Alloy

Metallurgical and Materials Transactions A - In this study, mechanisms of microstructural evolution during hot deformation of Ti-1100 were investigated by EBSD analysis. Misorientation angle...     

Nanomechanical and tribological behavior of hydroxyapatite reinforced ultrahigh molecular weight polyethylene nanocomposites for biomedical applications

A hydroxyapatite (HA) particulate reinforced ultrahigh molecular weight polyethylene (UHMWPE) nanocomposite is fabricated by internal mixer at 180°C and using of paraffin oil as a processing aid to overcome the high viscosity of melted UHMWPE. The reinforcing effects of nano‐HA are investigated on nanomechanical properties of HA/UHMWPE nanocomposites by nanoindentation and nanoscratching methods. Results show that the nanocomposite with 50 wt % nano‐HA exhibits a Young's modulus and hardness of 362.5% and 200% higher, and a friction coefficient of 38.86% lower than that of pure UHMWPE, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42052.     

Experimental and numerical results of dynamics behavior of a nonlinear piezoelectric beam

This article presents a numerical formulation and experimental implementation for the dynamics behavior verification of the nonlinear piezoelectric beam through harmonic excitation. The nonlinear piezoelectric beam dynamic analysis program is developed with MATLAB software. To verify the nonlinear piezoelectric beam dynamic analysis results, the experimental results are used for the vibration analysis of a piezoelectric beam to the harmonic excitation of the base of the beam. Then, the piezoelectric effect on the output voltage, velocity, acceleration values, and the time response are obtained. Afterwards, the effects of the excitation velocity and the position of concentrated mass on the output voltage are verified.     

高分散多壁碳纳米管增强铝基复合材料的制备(英文)

采用机械合金化技术制备高分散多壁碳纳米管(MWCNTs)-铝(Al)复合材料。将纯度99%的铝粉和质量分数2%的MWCNTs经超声和水平球磨处理使Al颗粒与MWCNTs间产生机械键合力。场发射SEM观察表明,MWCNTs分散在Al薄片的表面,随球磨时间的不同,颗粒大小和形貌各异。采用加压烧结手段将混合粉末加工成块体材料,其微观硬度测试表明,加入MWCNTs后Al基体的机械性能得到提高。     

Development of a Correlation Test Specimen for Highly Deformable Adhesive Systems

A new adhesive test specimen design was developed which embodied several key attributes, the most important of which was inclusion of tension, mixed-mode, and shear deformation mechanisms. The specimen design was easy to manufacture, required only simple tension testing equipment to test, and provided simple specimen geometry and boundary conditions for use in finite element model correlation exercises. By design, the individual failure points for each of the deformation mechanisms within the test specimen were separated and could be related directly to characteristics of the force versus displacement information from the experimental test. Finite element predictions using a Gurson constitutive model with element deletion at failure were generated and compared with experimental test results. It was found that while the order of failure modes within the prediction was the same as that found within the test, the element deletion technique yielded an abrupt change between failure modes not seen in the experimental test, and that a more complex numerical representation of failure would be a valuable development. Overall, the test specimen development was successful in providing a simple and repeatable method by which complex cohesive failure modes in a bonded system could be evaluated and correlated back to predictive tests.     

Effect of Sulfur Precursor on Dimensions of One-dimensional CdS Nanocrystals

One-dimensional CdS nanocrystals have been prepared by solvothermal method using cadmium acetate as a cadmium precursor,elemental sulfur and Na2S,as a sulfur precursor,and ethylenediamine as a solvent at 150℃ for 5 h.The nanocrystals were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM) and UV-Vis absorption spectroscopy.XRD patterns indicate that both Na2S and elemental sulfur as the sulfur precursor result in CdS nanorods with wurtzite phase(h...     

Formation kinetics of austenite in pearlitic ductile iron

This work evaluated the isothermal transformation of austenite in unalloyed pearlitic ductile iron and drew the isothermal phase diagram of austenitization in the ductile iron. Austenite forms at grain boundaries and then grows up to graphite regions during austenitiza-tion. The formation kinetics of austenite complies with the Avrami equation, in which the parameter (n) ranges from 4.71 to 4.99. The start time and finish time of transformation can be calculated at each temperature using the Avrami equation.     

Shear vibration and buckling of double-layer orthotropic nanoplates based on RPT resting on elastic foundations by DQM including surface effects

Microsystem Technologies - In this article, shear vibration and buckling of double-layer orthotropic nanoplates resting on elastic foundations are analyzed subjected to in-plane loadings including...     

Safety evaluation and antimicrobial properties of <Emphasis Type="Italic">Lactobacillus pentosus</Emphasis> 22C isolated from traditional yogurt

Traditional dairy products are the main source of probiotic microorganisms. Hence, this study aimed to evaluate the safety and antimicrobial potential of Lactobacillus pentosus 22C, isolated from traditional yogurt from Kermanshah province, Iran. Strain 22C showed no undesirable amino acid decarboxylase and β-hemolytic activities. Virulence associated genes were detected in the isolate. The strain produced an antimicrobial molecule named pentocin 22C, a small peptide with a relative mass between 5 and 10 kDa. Bacterial inhibition was pH-independent, with greater activity at pH 4–6. Purified or semi-purified antimicrobial agents can be used as bio-preservatives, and the producing strain can be used as a starter culture to improve food safety. Therefore, a biosafety assessment should be conducted. L. pentosus 22C, isolated from a traditional dairy product, has antimicrobial ability, although its safety must be evaluated.