20 research outputs found

    Visualization of Au Nanoparticles Buried in a Polymer Matrix by Scanning Thermal Noise Microscopy

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    We demonstrated visualization of Au nanoparticles buried 300 nm into a polymer matrix by measurement of the thermal noise spectrum of a microcantilever with a tip in contact to the polymer surface. The subsurface Au nanoparticles were detected as the variation in the contact stiffness and damping reflecting the viscoelastic properties of the polymer surface. The variation in the contact stiffness well agreed with the effective stiffness of a simple one-dimensional model, which is consistent with the fact that the maximum depth range of the technique is far beyond the extent of the contact stress field.Comment: 13 pages, 4 figures in main text; 7 pages, 5 figures in supplementary informatio

    Fundamental and higher eigenmodes of qPlus sensors with a long probe for vertical-lateral bimodal atomic force microscopy

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    The detection of vertical and lateral forces at the nanoscale by atomic force microscopy (AFM) reveals various mechanical properties on surfaces. The qPlus sensor is a widely used force sensor, which is built from a quartz tuning fork (QTF) and a sharpened metal probe, capable of high-resolution imaging in viscous liquids such as lubricant oils. Although a simultaneous detection technique of vertical and lateral forces by using a qPlus sensor is required in the field of nanotribology, it has still been difficult because the torsional oscillations of QTFs cannot be detected. In this paper, we propose a method to simultaneously detect vertical and lateral force components by using a qPlus sensor with a long probe. The first three eigenmodes of the qPlus sensor with a long probe are theoretically studied by solving a set of equations of motion for the QTF prong and probe. The calculation results were in good agreement with the experimental results. It was found that the tip oscillates laterally in the second and third modes. Finally, we performed friction anisotropy measurements on a polymer film by using a bimodal AFM utilizing the qPlus sensor with a long probe to confirm the lateral force detection

    Composite pheochromocytoma of the adrenal gland: a case series

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    Background: Composite pheochromocytoma is a rare pathological condition characterized by elements of both pheochromocytoma and neurogenic tumors. However, detailed clinical outcomes of this tumor have not been fully shown. From 2007 to 2013, we experienced three cases of adrenal composite pheochromocytoma. In this report, we investigate the clinicopathological features of these three cases of composite pheochromocytoma and compare them with previously reported cases. Case presentations: Cases 1 and 2 were a 29-year-old Japanese woman and a 59-year-old Japanese man, respectively. They underwent laparoscopic left adrenalectomy, and pathological examination revealed composite pheochromocytoma-ganglioneuroma. Case 3 was a 53-year-old Japanese man who had been receiving hemodialysis for 17 years. He underwent laparoscopic right adrenalectomy, and pathological examination revealed composite pheochromocytoma-ganglioneuroblastoma. Although the Ki67-positive rates varied from 1.0 to 6.2% among the three cases, no clinical recurrences occurred. Despite the relatively high rate of Ki67 positivity, complete tumor resection resulted in favorable clinical outcomes. Conclusion: We experienced three cases of adrenal composite pheochromocytoma. Although the clinical findings and treatment outcomes of composite pheochromocytoma were similar to those of ordinary pheochromocytoma, further studies of the biological behavior and genetic profiles of composite pheochromocytoma are necessary to achieve a better understanding of this tumor

    Visualization of subsurface nanoparticles in a polymer matrix using resonance tracking atomic force acoustic microscopy and contact resonance spectroscopy

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    A visualization technique of subsurface features with a nanometer-scale spatial resolution is strongly demanded. Some research groups have demonstrated the visualization of subsurface features using various techniques based on atomic force microscopy. However, the imaging mechanisms have not yet been fully understood. In this study, we demonstrated the visualization of subsurface Au nanoparticles buried in a polymer matrix 900 nm from the surface using two techniques; i.e., resonance tracking atomic force acoustic microscopy and contact resonance spectroscopy. It was clarified that the subsurface features were visualized by the two techniques as the area with a higher contact resonance frequency and a higher Q-factor than those in the surrounding area, which suggests that the visualization is realized by the variation of the contact stiffness and damping of the polymer matrix due to the existence of the buried nanoparticles
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