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degree of control over individual atoms and molecules, it is still possible to obtain structures with nanoscaled feature sizes. In comparison to the single structure nanotechnology, nanoscale bulk materials usually have smaller unit cell dimensions and these unit cells exhibit their desired properties only as members in the molecular collective. As the name "materials" suggest, further processing is needed to obtain a final functional result. Thus their function is not as specifically targeted as is the case for single nanostructures. There are many types of nanomaterials and nanotechnological products available today. ([26]) - Nanotubes, fullerenes or buckyballs as basis for nanocomposite materials - Nanocrystals, nanopowders and nanoparticulates (e.g. quantum dots). Applications include optical displays, computer memory, cryptography, photovoltaics, storage media, flexible electronics, telecommunications components, and quantum computing - Nanogels, aerogels, hydrogels and other nanoporous materials. Used for thermal insulation, as scaffolds for nanocomposite manufacturing, and to capture fragrances, chemical catalysts and biochemicals. - Nanofibers and nanowires Most nanocomposites consist of a matrix and a dispersed second phase in particulate, fibrous, or continuous form. This second phase may alter the nanomaterial’s electrical, thermal or magnetic properties, enhance its wear or erosion resistance or serve as a strengthening or stiffening agent. Single structure nanotechnology and bulk material nanotechnology tend to drift together as it is desirable to manufacture highly specialized nanostructures with less effort, more reproducibility and on a larger scale. For bulk material nanostructures a higher degree of control is desirable as well as the ability to add specialized functionality to specific subdomains. 2.4 Selected Issues in Nanotechnology As stated earlier in the introductory section, nanotechnology is a huge interdisciplinary field, spanning a large diversity of phenomena and approaches. Yet there exist a number of recurrent principles, ideas and problems accompanying the science of the small, some of which are mentioned here. 20
2.4.1 Self-Assembly and Emergent Structures Many of the nanoscale systems are produced in large quantities. The processing steps required (e.g. chemical additives, light, heat, altered solvent conditions) are often completed by and interact with behavior intrinsic to the building blocks themselves. This behavior emerges out of the interaction within the collection of atoms and molecules. Every day life examples are the alignment of the polar molecules to form the skin of soap bubbles or the growing of ice crystals when water is sufficiently cooled down. Similar processes happen at the nanoscale, when e.g. nanotubes start to grow at crystalline nucleation sites, when nanopores distribute themselves evenly in a material ([27]) or when proteins fold and self-assemble to attain their conformational structure required to perform their function. 2.4.2 Reliability Functional nanostructures should work reliably. That implies a reliable manufacturing method and means to test a finished device or material. Problems are adhesion, friction, wear, fracture, fatigue and contamination. Due to the high surface/volume ratio, devices with moving parts are particularly prone to stiction (high static friction). Furthermore not all material properties, e.g. for thin films, may be well known, making it difficult to predict their behavior and are possibly error prone. The tools from macroscopic domains may not longer work, classical mechanics (Young’s modulus of elasticity, hardness, bending strength, fracture toughness and fatigue life) must be partly replaced by molecular mechanics and finite element modeling to simulate the behavior nanosystems. As of today, there exist no fabrication standards for nanoscale devices and materials, making comparison difficult. Main techniques are rather experimental than state of the art. Storage issues, especially of MEMS and NEMS, as e.g. dust or debris can provoke failure. E.g. mechanical parts can be blocked or damaged or short-circuits provoked. ([8]) 2.4.3 Environmental Implications Because of their small size, nanoparticles can in certain cases penetrate cell membranes and integrate themselves into larger molecules. They can resist cellular defense systems but are large enough to interfere with cell processes. For example, in an inhalation experiments with rats, using 13 C-labeled particles, it was found that nanosized particles (∼ 25 nm) were taken up by the nerve cells and deposited in the central nervous system (CNS). Investigation also showed that these particles 21
Page 1 and 2: DIPLOMARBEIT Atomic Force Microscop
Page 3 and 4: »Later I have been asked many time
Page 5 and 6: Contents Abstract 4 1 Introduction
Page 7 and 8: 5.2.1 Optical Microscopy and Fluore
Page 9 and 10: theory (see e.g. [1]). Now I call o
Page 11 and 12: understand phenomena at a larger sc
Page 13 and 14: of whole dried Euglena cells in air
Page 15 and 16: these assembly functions for us. 2
Page 17 and 18: Figure 2.2: Rise in public spending
Page 19: The presented three types of nanote
Page 23 and 24: After diligent investigation such s
Page 25 and 26: 1 µN) between a probe and the samp
Page 27 and 28: 3.2.1 Static Mode In Static Mode (a
Page 29 and 30: crystal and the cantilever tip (pha
Page 31 and 32: Figure 3.6: Highly ordered and fres
Page 33 and 34: Figure 3.8: Schematic drawing of th
Page 35 and 36: Figure 3.11: The cantilever deflect
Page 37 and 38: Figure 3.14: This force curve shows
Page 39 and 40: Figure 4.1: A group of Euglena orga
Page 41 and 42: several species with rigid pellicle
Page 43 and 44: Figure 4.2: The rightmost cell can
Page 45 and 46: cavity and is used for regulatory f
Page 47 and 48: as phobic reactions, because the ce
Page 49 and 50: Figure 4.7: Scheme of the photorece
Page 51 and 52: Figure 4.9: Measured monoclinic uni
Page 53 and 54: Figure 4.11: Twice the same Euglena
Page 55 and 56: 4.15), their ends are termed the (-
Page 57 and 58: Figure 4.15: Kinesin and dynein and
Page 59 and 60: Figure 4.17: (Image reproduced from
Page 61 and 62: into fully functional chloroplasts
Page 63 and 64: Figure 4.19: How a microtubule-kine
Page 65 and 66: Chapter 5 Materials and Methods The
Page 67 and 68: Cell Treatment - Demembranation In
Page 69 and 70: Figure 5.3: This image shows cells
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Figure 5.4: The AFM setup at the In
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Figure 5.6: If the user menu AFM_TU
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Figure 5.7: Single steps of the sam
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Chapter 6 Results High resolution t
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Figure 6.2: An embedded E. gracilis
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Figure 6.5: Scanning under liquid s
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Flagellum The flagellum of an E. gr
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Pellicle The pellicle of E. gracili
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Figure 6.11: The pellicle of an E.
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Crystalline Cell Parts Crystalline
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Figure 6.18: A layered structure th
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It might also be possible that comb
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Appendix A Acronyms SPM Scanning Pr
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[13] A. Junk, F. Riess: From an ide
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[45] J. Ruan, B. Bhushan: Atomic-sc
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[70] M. Rief, M. Gautel, F. Oesterh
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[97] P. Gualtieri, L. Barsanti: Alg
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Annex 1 This Igor script was used i
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