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Liu P.,Shanghai JiaoTong University | Sun J.,Shanghai JiaoTong University | Zhao J.,Shanghai JiaoTong University | Liu X.,Shanghai JiaoTong University | And 4 more authors.
Journal of Synchrotron Radiation | Year: 2010

In vascular diseases, the involvement of small vessels can be very crucial physiologically. Morphological changes of vasculature and alterations may be promising characteristic criteria for investigating disease progression and for evaluating therapeutic effects. Visualization of microvasculatures is an important step in understanding the mechanism of early vessel disorders and developing effective therapeutic strategies. However, the microvessels involved are beyond the detection limit of conventional angiography, i.e. 200 m. Thus, faster and higher-resolution imaging technologies are desired to capture the early anatomical structure changes of vasculatures in study of the disease. A new angiography system, synchrotron radiation microangiography, has been developed in this study. It allows for enhanced sensitivity to contrast agents and superior image quality in spatial resolution. Iodine and barium sulfate were used as blood vessel contrast agents. Physiological features of whole-body mouse microvasculature were investigated using synchrotron radiation for the first time. The intracranial vascular network and other blood vessels were observed clearly, and the related anatomy and vessel diameters were studied. Dynamic angiography in mouse brain was performed with a high spatial image resolution of around 20-30 m. Future research will focus on the development of novel specific targeting contrast agents for blood vessel imaging in vivo with a long half-life and fewer side effects. © 2010 International Union of Crystallography Printed in Singapore - all rights reserved. Source

Li Y.C.,Hefei University of Technology | Xu F.,Hefei University of Technology | Hu X.F.,Hefei University of Technology | Kang D.,Hefei University of Technology | And 2 more authors.
Acta Materialia | Year: 2014

In situ investigation of the microstructure evolution and the mixed-interaction mechanisms of metal-ceramic materials during the microwave sintering process was carried out using the synchrotron radiation computed tomography technique. The results indicate that there are some special mixed-interaction mechanisms, which may promote the sintering process during the microwave heating of metal-ceramic materials. In the experiment, some particular sintering phenomena that differ from the microwave sintering of pure metal materials were observed, such as fast interface bonding and particle swallowing. Quantitative analysis of the microstructure evolution during microwave sintering showed that the decrement of grain surface bending energy of metal-ceramic materials was slower, while the sintering-neck growth rate was higher than that of the pure metal materials. These results may be caused by the mixed-interaction mechanisms between microwave and metal-ceramic materials, such as the "micro-focusing effect", the special microwave interaction mechanisms on the particle surface and the heterogeneous metal-ceramic interface. This study will help to provide a useful reference for the improvement of the microstructure characteristics of metal-ceramic materials in microwave sintering. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Source

He Z.,Jiangsu University | Zhong W.,Jiangsu University | Wang Q.,Jiangsu University | Jiang Z.,Jiangsu University | Fu Y.,Shanghai Synchrotron Radiation Facility
Applied Thermal Engineering | Year: 2013

In diesel engines, the cavitating flow in nozzles greatly affects the fuel atomization characteristics and then the subsequent combustion and exhaust emissions. In this paper, with the needle lift curve on the basis of injection rate experimental data, a moving mesh generation strategy was applied for 3D simulation of the nozzle cavitating flow. Based on the third-generation synchrotrons of Shanghai Synchrotron Radiation facility (SSRF), a high-precision three-dimension structure of testing nozzle with detailed internal geometry information was obtained using X-ray radiography for a more accurate simulation. A flow visualization experiment system with a transparent scaled-up vertical multi-hole injector nozzle tip was setup. The experimental data was obtained to make a comparison to validate the calculated results and good qualitative agreement was shown between them. Afterward, the effects of needle movement on development of the cavitating flow and flow characteristics parameters were investigated. Finally, the influence of fuel temperature on development of the cavitating flow was also studied. Research of the flow characteristics for the diesel and biodiesel revealed that the flow characteristics of the biodiesel with a temperature rise of between 50 K and 60 K in injector nozzles will be similar to those of the diesel fuel. © 2013 Elsevier Ltd. All rights reserved. Source

Hu X.,University of Chinese Academy of Sciences | Wang L.,University of Chinese Academy of Sciences | Xu F.,University of Chinese Academy of Sciences | Xiao T.,Shanghai Synchrotron Radiation Facility | Zhang Z.,CAS National Center for Nanoscience and Technology
Carbon | Year: 2014

In contrast with traditional methods of observation, synchrotron radiation X-ray computed tomography (SR-CT) is an advanced technique that allows direct three-dimensional (3D) and non-destructive observation of microstructures in materials. High-resolution in situ observations (0.7 μm/pixel) of fractures in short carbon fiber/epoxy composites are achieved using the SR-CT technique, and the mechanical load response of short carbon fibers treated with oxidation and those untreated are compared. By the quantitative extraction and analysis of microstructure parameters in high-resolution 3D images, the failure mechanisms of the two materials were studied. The proportion of broken fibers to other types of fiber damage in the sample with oxidation-treated fibers increases by about 6%. Also, the oxidation treatment is able to reduce the ineffective length of the fibers by about 20%, thereby improving the mechanical properties of these composites. The results show that computed tomography can promote characterization of the internal microstructures in carbon fiber-reinforced polymer composites, which will facilitate further theoretical research on the failure mechanisms of these composites. © 2013 Elsevier Ltd. All rights reserved. Source

Shen C.,Zhejiang University | Chen H.,Zhejiang University | Wu S.,Zhejiang University | Wen Y.,Zhejiang University | And 4 more authors.
Journal of Hazardous Materials | Year: 2013

Metal-biopolymer complexes has recently gained significant attention as an effective adsorbent used for the removal of Cr(VI) from water. Unfortunately, despite increasing research efforts in the field of removal efficiency, whether this kind of complex can reduce Cr(VI) to less-toxic Cr(III) and what are the mechanisms of detoxification processes are still unknown. In this study, despite the highly adsorption efficiency (maximum adsorption capacity of 173.1. mg/g in 10. min), the significant improvement of Cr(VI) reduction by chitosan-Fe(III) complex compared with normal crosslinked chitoan has been demonstrated. In addition, the structure of chitosan-Fe(III) complex and its functional groups concerned with Cr(VI) detoxification have been characterized by the powerful spectroscopic techniques X-ray absorption fine structure (XAFS) and X-ray photoelectron spectroscopy (XPS). The XPS spectra indicated that the primary alcoholic function on C-6 served as an electron donor during Cr(VI) reduction and was oxidized to a carbonyl group. The X-ray adsorption near edge spectra (XANES) of the Cr(VI)-treated chitosan-Fe(III) complex revealed the similar geometrical arrangement of Cr species as that in Cr(III)-bound chitosan-Fe(III). Overall, a possible process and mechanism for highly efficient detoxification of Cr(VI) by chitosan-Fe(III) complex has been elucidate. © 2012 Elsevier B.V. Source

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