The design and fabrication processes of a novel scanner with minimized coupling motions for a high-speed atomic force microscope （AFM） were addressed. An appropriate design modification was proposed through the anal...The design and fabrication processes of a novel scanner with minimized coupling motions for a high-speed atomic force microscope （AFM） were addressed. An appropriate design modification was proposed through the analyses of the dynamic characteristics of existing linear motion stages using a dynamic analysis program, Recurdyn. Because the scanning speed of each direction may differ, the linear motion stage for a high-speed scanner was designed to have different resonance frequencies for the modes, with one dominant displacement in the desired directions. This objective was achieved by using one-direction flexure mechanisms for each direction and mounting one stage for fast motion on the other stage for slow motion. This unsymmetrical configuration separated the frequencies of two vibration modes with one dominant displacement in each desired direction, and hence suppressed the coupling between motions in two directions. A pair of actuators was used for each axis to decrease the crosstalk between the two motions and give a sufficient force to actuate the slow motion stage, which carried the fast motion stage, A lossy material, such as grease, was inserted into the flexure hinge to suppress vibration problems that occurred when using an input triangular waveforrn. With these design modifications and the vibration suppression method, a novel scanner with a scanning speed greater than 20 Hz is achieved.展开更多
The hydration film on particle surface plays an important role in bubble-particle adhesion in mineral flotation process. The thicknesses of the hydration films on natural hydrophobic coal and hydrophilic mica surfaces...The hydration film on particle surface plays an important role in bubble-particle adhesion in mineral flotation process. The thicknesses of the hydration films on natural hydrophobic coal and hydrophilic mica surfaces were measured directly by atomic force microscopy (AFM) based on the bending mode of the nominal constant compliance regime in AFM force curve in the present study. Surface and solid-liquid interfacial energies were calculated to explain the forming mechanism of the hydration film and atomic force microscopy data. The results show that there are significant differences in the structure and thickness of hydration films on coal and mica surfaces. Hydration film formed on mica surface with the thickness of 22.5 nm. In contrast, the bend was not detected in the nominal constant compliance regime. The van der Waals and polar interactions between both mica and coal and water molecules are characterized by an attractive effect, while the polar attractive free energy between water and mica (-87.36 mN/m) is significantly larger than that between water and coal (-32.89 mN/m), which leads to a thicker and firmer hydration layer on the mica surface. The interfacial interaction free energy of the coal/water/bubble is greater than that of mica. The polar attractive force is large enough to overcome the repulsive van der Waals force and the low energy barrier of film rupture, achieving coal particle bubble adhesion with a total interfacial free energy of-56.30 mN/m.展开更多
目的以课题组纯化获得的蛋白样本为观察对象,对比原子力显微镜(atomic force microscope,AFM)及扫描电子显微镜(scanning electron microscope,SEM)的观察结果,并总结AFM观察生物大分子的主要问题和解决方法。方法将蛋白样本使用PBS稀释...目的以课题组纯化获得的蛋白样本为观察对象,对比原子力显微镜(atomic force microscope,AFM)及扫描电子显微镜(scanning electron microscope,SEM)的观察结果,并总结AFM观察生物大分子的主要问题和解决方法。方法将蛋白样本使用PBS稀释至15 nmol·L^(-1),分别固定于载玻片、硅片和云母片上烘干,制成固相观察样本,SEM样本在观察前镀铂,使用AFM及SEM观察蛋白质表面结构,计算样本高度,对比结果差异。结果带正电的蛋白样本在观察时由于AFM探针的斥力会向右偏移;云母片能很好地消除蛋白正电荷从而避免样本移动;PBS能为蛋白样本提供良好的稳定环境,但PBS盐结晶会干扰探针运行和成像清晰度;SEM样本需要镀铂后观察,无法达到AFM的精度。结论使用AFM和SEM均可在体外环境直接观察蛋白质结构,AFM能提供更高精度的观察结果;在蛋白样本稳定性允许的情况下首选超纯水为溶剂载体,乙醇等挥发性液体也可作为溶剂载体,AFM的应用可为药理学生物大分子互作研究提供一新途径。展开更多
弛豫铁电体因其卓越的介电和压电特性,在传感器、光电器件、高密度存储器、类脑计算等领域展现出广泛的应用潜力。然而,纳米尺度超薄膜的弛豫特性研究受到严重漏电流的限制,基于Sawyer-Tower电路和Positive-Up-Negative-Down(PUND)脉冲...弛豫铁电体因其卓越的介电和压电特性,在传感器、光电器件、高密度存储器、类脑计算等领域展现出广泛的应用潜力。然而,纳米尺度超薄膜的弛豫特性研究受到严重漏电流的限制,基于Sawyer-Tower电路和Positive-Up-Negative-Down(PUND)脉冲波形的测试方法存在显著挑战。本研究提出了一种基于压电力显微镜(Piezoresponse Force Microscopy, PFM)的测试方法,来研究纳米尺度弛豫薄膜的极化特性。以Pb(Mg,Nb)O_(3)-PbTiO_(3)(PMN-PT)超薄膜为例,比较了不同厚度的PMN-PT弛豫薄膜与铁电Pb(Zr,Ti)O_(3)(PZT)薄膜在双频追踪PFM(DART-PFM)测量中On-field和Off-field两种模式下的极化回滞行为。通过调节PFM回线测量中的用于极化读出的交流信号电压振幅,系统表征了纳米厚度PMN-PT薄膜的弛豫特性。进一步对不同面内应变和厚度的PMN-PT超薄膜进行PFM测试,发现在较大压缩应变(3.19%)下,弛豫特性被抑制,表现出显著的铁电特性,并观测到铁电-弛豫转变的临界厚度。这些实验结果验证了所提出测试方法的有效性。本研究不仅为超薄膜弛豫特性的探索提供了一种新的表征方法,也为理解铁电材料的弛豫极化行为奠定了基础,推动了弛豫铁电材料在低维电子学器件中的应用。展开更多
基金Work(R0A-2007-000-20042-0) partly supported by the Second Stage of Brain Korea 21 Projectspartly by the Korea Science and Engineering Foundation (KOSEF) through the National Research Laboratory Program funded by the Ministry of Science and Technology of Korea
文摘The design and fabrication processes of a novel scanner with minimized coupling motions for a high-speed atomic force microscope （AFM） were addressed. An appropriate design modification was proposed through the analyses of the dynamic characteristics of existing linear motion stages using a dynamic analysis program, Recurdyn. Because the scanning speed of each direction may differ, the linear motion stage for a high-speed scanner was designed to have different resonance frequencies for the modes, with one dominant displacement in the desired directions. This objective was achieved by using one-direction flexure mechanisms for each direction and mounting one stage for fast motion on the other stage for slow motion. This unsymmetrical configuration separated the frequencies of two vibration modes with one dominant displacement in each desired direction, and hence suppressed the coupling between motions in two directions. A pair of actuators was used for each axis to decrease the crosstalk between the two motions and give a sufficient force to actuate the slow motion stage, which carried the fast motion stage, A lossy material, such as grease, was inserted into the flexure hinge to suppress vibration problems that occurred when using an input triangular waveforrn. With these design modifications and the vibration suppression method, a novel scanner with a scanning speed greater than 20 Hz is achieved.
基金Project(2014BAB01B03)supported by the National Key Technology R&D Program During the 12th Five-Yean Plan of ChinaProject(51774286)supported by the National Natural Science Foundation of ChinaProject(BK20150192)supported by the Natural Science Foundation of Jiaaagsu Province,China
文摘The hydration film on particle surface plays an important role in bubble-particle adhesion in mineral flotation process. The thicknesses of the hydration films on natural hydrophobic coal and hydrophilic mica surfaces were measured directly by atomic force microscopy (AFM) based on the bending mode of the nominal constant compliance regime in AFM force curve in the present study. Surface and solid-liquid interfacial energies were calculated to explain the forming mechanism of the hydration film and atomic force microscopy data. The results show that there are significant differences in the structure and thickness of hydration films on coal and mica surfaces. Hydration film formed on mica surface with the thickness of 22.5 nm. In contrast, the bend was not detected in the nominal constant compliance regime. The van der Waals and polar interactions between both mica and coal and water molecules are characterized by an attractive effect, while the polar attractive free energy between water and mica (-87.36 mN/m) is significantly larger than that between water and coal (-32.89 mN/m), which leads to a thicker and firmer hydration layer on the mica surface. The interfacial interaction free energy of the coal/water/bubble is greater than that of mica. The polar attractive force is large enough to overcome the repulsive van der Waals force and the low energy barrier of film rupture, achieving coal particle bubble adhesion with a total interfacial free energy of-56.30 mN/m.
文摘目的以课题组纯化获得的蛋白样本为观察对象,对比原子力显微镜(atomic force microscope,AFM)及扫描电子显微镜(scanning electron microscope,SEM)的观察结果,并总结AFM观察生物大分子的主要问题和解决方法。方法将蛋白样本使用PBS稀释至15 nmol·L^(-1),分别固定于载玻片、硅片和云母片上烘干,制成固相观察样本,SEM样本在观察前镀铂,使用AFM及SEM观察蛋白质表面结构,计算样本高度,对比结果差异。结果带正电的蛋白样本在观察时由于AFM探针的斥力会向右偏移;云母片能很好地消除蛋白正电荷从而避免样本移动;PBS能为蛋白样本提供良好的稳定环境,但PBS盐结晶会干扰探针运行和成像清晰度;SEM样本需要镀铂后观察,无法达到AFM的精度。结论使用AFM和SEM均可在体外环境直接观察蛋白质结构,AFM能提供更高精度的观察结果;在蛋白样本稳定性允许的情况下首选超纯水为溶剂载体,乙醇等挥发性液体也可作为溶剂载体,AFM的应用可为药理学生物大分子互作研究提供一新途径。
文摘弛豫铁电体因其卓越的介电和压电特性,在传感器、光电器件、高密度存储器、类脑计算等领域展现出广泛的应用潜力。然而,纳米尺度超薄膜的弛豫特性研究受到严重漏电流的限制,基于Sawyer-Tower电路和Positive-Up-Negative-Down(PUND)脉冲波形的测试方法存在显著挑战。本研究提出了一种基于压电力显微镜(Piezoresponse Force Microscopy, PFM)的测试方法,来研究纳米尺度弛豫薄膜的极化特性。以Pb(Mg,Nb)O_(3)-PbTiO_(3)(PMN-PT)超薄膜为例,比较了不同厚度的PMN-PT弛豫薄膜与铁电Pb(Zr,Ti)O_(3)(PZT)薄膜在双频追踪PFM(DART-PFM)测量中On-field和Off-field两种模式下的极化回滞行为。通过调节PFM回线测量中的用于极化读出的交流信号电压振幅,系统表征了纳米厚度PMN-PT薄膜的弛豫特性。进一步对不同面内应变和厚度的PMN-PT超薄膜进行PFM测试,发现在较大压缩应变(3.19%)下,弛豫特性被抑制,表现出显著的铁电特性,并观测到铁电-弛豫转变的临界厚度。这些实验结果验证了所提出测试方法的有效性。本研究不仅为超薄膜弛豫特性的探索提供了一种新的表征方法,也为理解铁电材料的弛豫极化行为奠定了基础,推动了弛豫铁电材料在低维电子学器件中的应用。
