ARM嵌入式系统在纳米操作系统中的应用研究

近年来，随着微纳米科技的迅速发展，机电产品有望向更微观化、高性能化发展，这将促进材料、制造、电子、生物医学、信息等领域新的科学技术出现，在新的科学技术层次上为可持续发展的理论提供物质和技术保障。微纳米科技最终目标是研究和发现微纳尺度物质所具有的新颖的物理、化学和生物学现象与特性。并以此为基础来设计、制作、组装成新的材料、组件或系统，实现与之相应的特定功能，促进新的科学技术发展与变革，这无疑具有十分重要的科学意义和经济价值。而实现这个目标的使能技术便是微纳米尺度下观测、操作和装配的科学方法与相关的技术和装备，因此开展微纳米操作研究具有特别重要的意义。微纳米操作是微纳米制造科学技术的重要内容之一，使用探针模式的机器人化微纳操作方法，实现在微纳米尺度物体的可控操作，对促进我国微纳米科学技术发展具有特别重要的意义。 目前已有的基于探针的纳米技术装置如SPM (Scanning Probe Microscope)是基于探针模式的纳米观测基本装置。在此基础上研究发展的基于探针的纳米操作已成为纳米科技研究的新领域，是目前世界上各国正在大力开发的前沿研究课题。但目前市场上的SPM等纳米观测设备缺乏驱动控制与信息交互功能和开放界面，限制了用户在此基础上开发纳米操作、装配等功能的能力，因而研究具有信息交互能力的、可进行在线操作控制与宏-微-纳观信息交互的纳米操作监控系统，进而发展成具有自动化/机器人化功能的纳米作业系统队纳米科学技术发展、纳米制造的实现无疑具有重要意义。本论文的科研内容是以面向纳米制造的机器人化系统为研究背景，在自主技术的基础上，开展应用ARM嵌入式系统构成纳米作业系统的实时控制器研究。实时多任务的操作控制系统是纳米作业系统的核心技术，可以实时进行基于探针的传感信息采集、状态反馈控制、形貌观测数据生成、作业运动轨迹生成、位置反馈控制等功能的数据处理与实现。本论文重点介绍以SAMSUNG公司的ARM9处理器芯片S3C2410为嵌入式控制器系统的核心，在移植嵌入式Linux作为操作系统的基础上，开发具有实时数据采集与控制指令、通信功能的人机交互界面。基于ARM的实时控制器的研究为探针模式的纳米观测与操作系统开发提供了关键技术，可以提供开放的AFM系统，促进操作型纳米系统的研究与实现，可以保证纳米观测与操作控制的实时性，可以为纳米作业控制方法提供方便的编程、开发功能。本论文主要研究了面向纳米作业的基于ARM嵌入式实时控制器硬件结构及软件系统的研究与开发过程。首先介绍嵌入式系统的基本概念和特点；其次介绍基于SPM模式的纳米操作系统性能与技术特点；第三，根据纳米作业系统的技术功能要求，详细介绍了具有实时多任务管理功能的硬件系统的设计，重点解决核心板和扩展板各部分功能模块的设计；第四，详细介绍了嵌入式Linux操作系统下的应用程序开发模式及开发过程；最后，详细介绍了嵌入式Linux操作系统下的应用程序开发，主要工作是完成SPM纳米操作系统中的ARM开发平台的功能接口模块的调试及Linux系统下多线程技术在本系统中的应用。本次毕业设计已完成ARM开发平台在整个SPM纳米操作系统中要实现的各个功能模块，结合SPM纳米操作系统的实时性问题，进行了ARM开发平台的系统软件架构分析和利用多线程技术的以太网通信实验，在一定程度上提高了纳米操作系统中的实时性和成像质量。

基于机械力与电场的AFM纳米操作/加工研究

纳米技术是在纳米尺度上研究物质的特性和相互作用，以及利用这些特性的多学科交叉的新兴科学技术。纳米加工技术是对纳米技术的重要应用，它使人类在纳米尺度上进行结构和器件的制造成为可能。基于原子力显微镜(AFM)的纳米加工是近20年来发展的技术，由于AFM具有许多新颖的技术特点(如高分辨率，可操控等)，因而基于AFM的纳米加工技术成为纳米科学研究的新热点。 本论文以纳米制造为背景，围绕基于AFM的纳米加工技术所涉及的科学问题，重点开展了基于机械力的AFM纳米操作和基于电场的AFM纳米加工的理论方法和实现技术研究。在这些研究的基础上，开展了基于纳观机械力的刻划、纳米颗粒的排列、碳纳米管的装配实验研究，开展了基于微观电场的氧化点、氧化线、氧化文字的加工实验研究，以及微观电场氧化切割、焊接加工方法的研究。 本文的主要内容包括：交互式纳米操作系统的构建，基于机械力的AFM纳米操作研究，基于电场的AFM纳米加工研究，基于机械力与电场的AFM纳米操作/加工实验研究。具体如下： 在商用AFM的基础上，研究并搭建了具有力觉与视觉反馈的交互式纳米操作系统。通过该系统操作者可以实时感觉到操作中作用在AFM针尖的纳观力并控制针尖的运动，还可以实时观察到模拟出的针尖操作过程，因而显著提高了纳米操作的直观性、可靠性及效率。 在基于机械力的AFM纳米操作研究方面，为了理解纳观环境下普遍存在的黏附力特性，对AFM的力曲线进行了分析并给出了详细解释；通过研究探针悬臂的形变，提出了探针所受三维作用力的建模方法，以此模型获得了操作中的纳观力信息；基于多刚体动力学理论提出了碳纳米管的二连杆动力学建模方法，并对碳纳米管在操作中的弯曲特性进行了仿真分析。这些研究为基于机械力的AFM纳米操作提供了理论指导。 在基于电场的AFM纳米加工方面，研究了微观电场在样本表面的分布，建立了电场氧化加工中电场分布模型，以此模型分析了氧化物特性与电场分布的关系；对氧化加工中氧化物生长过程进行了动力学分析，得到了氧化物生长的理论模型；系统地研究了氧化加工中各因素(偏压，加工速度，针尖－样本距离等)对氧化结构生成的影响，总结了氧化物的生成与各因素的关系，验证了理论分析的结果，提高了电场氧化加工的重复性及可控性。这些研究为基于电场的AFM纳米加工提供了理论及实验依据。 在基于机械力与电场的AFM纳米操作/加工理论研究的基础上，进行了相关的实验研究。通过基于机械力的AFM纳米操作方法实现了在样本表面刻划文字，纳米颗粒的排列，碳纳米管的操作及装配；通过基于电场的AFM纳米加工方法实现了在样本表面加工氧化点，氧化线及氧化文字等纳米结构。利用电场氧化加工方法还实现了对碳纳米管的定点切割与焊接，拓展了AFM纳米加工的应用领域。这些实验研究验证了系统的操作及装配性能，证明了电场加工的有效性及具有潜在的应用前景。 本文的研究工作为制造纳米结构、纳米器件提供了一条可行的技术途径，对AFM纳米加工技术的进一步发展具有一定的理论参考及实践指导意义。

Melhoria dos canais de comunicação da cadeia de suprimentos no setor de patrimônio e materiais (SPM) da Embrapa Florestas.

2010

Les Signaux Post Mortem (SPM) de l’apoptose endothéliale : des acteurs du remodelage vasculaire

L’immunosuppression a permis d’améliorer l’incidence du rejet aigu sans toutefois améliorer significativement le rejet chronique. Celui-ci est caractérisé par une vasculopathie du greffon (VG) similaire à une forme accélérée d’athérosclérose native accompagnée de fibrose. La pathophysiologie de la VG découle de l’hypothèse de réponse à l’insulte proposée par Russell Ross en 1977. Selon son postulat, l’endothélium stressé par des facteurs immunologiques et non immunologiques initie l’apoptose endothéliale suivi d’une réponse de réparation vasculaire via un épaississement myo-intimal aux sites d’insultes. Toutefois, lorsque les stress endothéliaux initiaux demeurent soutenus, l’apoptose endothéliale et la réponse de réparation perpétuent. Compte tenu que l’inhibition de l’apoptose endothéliale bloque le développement de la VG in vivo, notre hypothèse de travail reposait sur les répercussions paracrines de l’apoptose endothéliale sur les types cellulaires participant au remodelage vasculaire. Nous avons généré un système expérimental in vitro afin d’induire l’apoptose endothéliale en absence significative de nécrose cellulaire. À l’aide d’une approche protéomique multidimensionnelle et comparative, nous avons démontré que les cellules endothéliales apoptotiques exportent spécifiquement 27 signaux post mortem (SPM). Nous avons démontré que certains de ces SPM ont des propriétés anti-apoptotiques (TCTP et EGF), d’autre fibrogénique (CTGF), récapitulant ainsi certains phénotypes cellulaires associés au développement de la VG. Parmi les médiateurs identifiés, 16 n’avaient pas de signal de sécrétion, incluant TCTP, suggérant que des mécanismes de sécrétion non conventionnels soient favorisés durant l’apoptose. Nous avons démontré que la caspase-3 effectrice régule la voie de sécrétion non classique exosomiale associée à l’export extracellulaire de nanovésicules TCTP+VE, anti-apoptotiques et biochimiquement distinctes des corps apoptotiques. Finalement, l’ensemble des données protéomiques ont permis d’émettre l’hypothèse qu’en réponse à un stress apoptotique, la cellule exporte différents médiateurs (solubles et vésiculaires) de manière non conventionnelle nécessitant la fusion d’organelles de la voie endocytaire et autophagique avec la membrane plasmique. Ce mécanisme serait régulé durant la phase effectrice de l’apoptose permettant ainsi d’initier une réponse de réparation extracellulaire seulement lorsque le destin cellulaire a atteint un point de non retour. Ainsi, le testament protéique et nanovésiculaire légué durant l’apoptose endothéliale pourrait servir simultanément de biomarqueur de la VG et de cible thérapeutique afin de diminuer le remodelage vasculaire pathologique.

New insights on growth mechanisms of protein clusters at surfaces: an AFM and simulation study

Despite its relevance to a wide range of technological and fundamental areas, a quantitative understanding of protein surface clustering dynamics is often lacking. In inorganic crystal growth, surface clustering of adatoms is well described by diffusion-aggregation models. In such models, the statistical properties of the aggregate arrays often reveal the molecular scale aggregation processes. We investigate the potential of these theories to reveal hitherto hidden facets of protein clustering by carrying out concomitant observations of lysozyme adsorption onto mica surfaces, using atomic force microscopy. and Monte Carlo simulations of cluster nucleation and growth. We find that lysozyme clusters diffuse across the substrate at a rate that varies inversely with size. This result suggests which molecular scale mechanisms are responsible for the mobility of the proteins on the substrate. In addition the surface diffusion coefficient of the monomer can also be extracted from the comparison between experiments and simulations. While concentrating on a model system of lysozyme-on-mica, this 'proof of concept' study successfully demonstrates the potential of our approach to understand and influence more biomedically applicable protein-substrate couples.

AFM analysis of bleaching effects on dental enamel microtopography

The purpose of this in vitro study was to test a new methodology to evaluate the effects of 35% hydrogen peroxide agent on the microtopography of sound enamel using an atomic force microscope (AFM). The buccal sound surfaces of three extracted human lower incisors were used, without polishing the surfaces to maintain them with natural morphology. These unpolished surfaces were subjected to bleaching procedure with 35% hydrogen peroxide that consisted of 4 applications of the bleaching agent on enamel surfaces for 10 min each application. Surface images were obtained in a 15 mu m x 15 mu m area using an AFM. The roughness (Ra and RMS) and the power spectral density (PSD) were obtained before and after the bleaching treatment. As results we could inquire that the PSD analyses were very suitable to identifying the morphological changes on the surfaces, while the Ra and RMS parameters were insufficient to represent the morphological alterations promoted by bleaching procedure on enamel. The morphological wavelength in the range of visible light spectrum(380-750 nm) was analyzed, showing a considerable increase of the PSD with the bleaching treatment. (C) 2009 Elsevier B. V. All rights reserved.

TEM, XRD and AFM study of poly(o-ethoxyaniline) films: new evidence for the formation of conducting islands

The existence of conducting islands in polyaniline films has long been proposed in the literature, which would be consistent with conducting mechanisms based on hopping. Obtaining direct evidence of conducting islands, however, is not straightforward. In this paper, conducting islands were visualized in poly(o-ethoxyaniline) (POEA) films prepared at low pH, using Transmission Electron Microscopy (TEM) and atomic force spectroscopy (AFS). The size of the islands varied between 67 and 470 angstrom for a pH=3.0, with a larger average being obtained with AFS, probably due to the finite size effect of the atomic force microscopy tip. In AFS, the conducting islands were denoted by regions with repulsive forces due to the double-layer forces. On the basis of X-ray diffraction (XRD) patterns for POEA in the powder form, we infer that the conducting islands are crystalline, and therefore a POEA film is believed to consist of conducting islands dispersed in an insulating, amorphous matrix. From conductivity measurements we inferred the charge transport to be governed by a typical quasi-one dimensional variable range hopping (VRH) mechanism.

Deposition of selenium thin layers on gold surfaces from sulphuric acid media: Studies using electrochemical quartz crystal microbalance, cyclic voltammetry and AFM

In this paper we report here new considerations about the relationship between the mass and charge variations (m/z relationship) in underpotential deposition (UPD), bulk deposition and also in the H(2)Se formation reaction. Nanogravimetric experiments were able to show the adsorption of H(2)SeO(3) on the AuO surface prior to the voltammetric sweep and that, after the AuO reduction, 0.40 monolayer of H(2)SeO(3) remains adsorbed on the newly reduced Au surface, which was enough to gives rise to the UPD layer. The UPD results indicate that the maximum coverage with Se(ads) on polycrystalline gold surface corresponds to approximately 0.40 monolayer, in good agreement with charge density results. The cyclic voltammetry experiments demonstrated that the amount of bulk Se obtained during the potential scan to approximately 2 Se monolayers, which was further confirmed by electrochemical quartz crystal microbalance (EQCM) measurements that pointed out a mass variation corresponding of 3 monolayers of Se. In addition, the Se thin films were obtained by chronoamperometric experiments, where the Au electrode was polarized at +0.10V during different times in 1.0 M H(2)SO(4) + 1.0 mM SeO(2). The topologic aspects of the electrodeposits were observed in Atomic Force Microscope (AFM) measurements. Finally, in highly negative potential polarizations, the H(2)Se formation was analyzed by voltammetric and nanogravimetric measurements. These finding brings a new light on the selenium electrodeposition and point up to a proposed electrochemical model for molecule controlled surface engineering. (c) 2009 Elsevier Ltd. All rights reserved.

Investigation of the interaction between Tc85-11 protein and antibody anti-T cruzi by AFM and amperometric measurements

This present work reports on development of an amperometric immunosensor for the diagnosis of Chagas' disease using a specific glycoprotein of the trypomastigote surface, which belongs to the Tc85-11 protein family of Trypanosoma cruzi (T cruzi). An atomically flat gold surface on a silicon substrate and gold screen-printed electrodes were functionalized with cystatrine and later activated with glutaraldehyde (GA), which was used to form covalent bonds with the purified recombinant antigen (Tc85-11). The antigen reacts with the antibody from the serum, and the affinity reaction was monitored directly using atomic force microscopy or amperometry through a secondary antibody tagged to peroxidase (HRP). Surface imaging allowed to us to differentiate the modification steps and antigen-antibody interaction allowed to distinguish the affinity reactions. In the amperometric immunosensor, peroxidase catalyses the L-2 formation in the presence of hydrogen peroxide and potassium iodide, and the reduction current intensity was measured at a given potential with screen-printed electrodes. The immunosensor was applied to sera of chagasic patients and patients having different systemic diseases. (c) 2006 Elsevier Ltd. All rights reserved.