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Bābol, Iran

Moghaddam H.M.,University of Mazandaran | Moghaddam H.M.,Nanotechnology Group
Pramana - Journal of Physics | Year: 2011

Electronic properties of single-walled boron nitride nanotube in zig-zag form are numerically investigated by replacing B atoms with C atoms. Using a tight-binding Hamiltonian, the methods based on Green's function theory, Landauer formalism and Dyson equation, the electronic density of states and electronic conductance in boron nitride nanotube and boron carbonitride nanotube are calculated. Our calculations indicate that in a boron nitride nanotube, the localized states associated with C impurities appear as the concentration of C atoms increases. The boron carbonitride nanotube thus behaves like a semiconductor. Also, by increasing the C atom concentration, the voltage in the first step on the I-V characteristics decreases, whereas the corresponding current increases. © Indian Academy of Sciences.

Butterworth J.A.,University of Colorado at Boulder | Pao L.Y.,University of Colorado at Boulder | Abramovitch D.Y.,Nanotechnology Group
Proceedings of the 2010 American Control Conference, ACC 2010 | Year: 2010

In previous work, we evaluated the performance of two control architectures applied to atomic force microscopes (AFM) [1]. Experimental results in [1] indicated that the closed-loop-injection (FFCLI) architecture outperformed the plant-injection (FFPI) architecture when using a specific model-inversion feedforward technique for the tracking of a raster pattern. Empirical work suggested that a nontraditional variation upon the experimentally inferior FFPI architecture may allow it to track a raster pattern at a performance level in the neighborhood of the FFCLI architecture. This variation is manifested as additional delay inserted in the feedforward control system. An online adaptive technique is used to determine the required amount of additional delay. Experimental results show that the performance level of the FFCLI architecture and the adaptive-delay FFPI architecture are comparable. © 2010 AACC.

Kardous F.,Nanotechnology Group | Kardous F.,University of Franche Comte | Yahiaoui R.,CNRS Femto ST Institute | Aoubiza B.,University of Franche Comte | Manceau J.-F.,CNRS Femto ST Institute
Sensors and Actuators, A: Physical | Year: 2014

Liquid mixing at micro-scale is considered a challenge which is even tougher to overcome in the case of discrete microfluidic. Many researchers have developed strategies and tried to be pioneer in mixing solutions for lab on chip. In this paper, we present a parallel microdroplet mixer based on acoustic field generation using a low frequency vibration (up to few hundreds of kilohertz). This device can be used for lab on chip applications, since the liquid characteristics are not disturbed by the plugged energy and involve relatively simple microfabrication techniques. We designed, fabricated, evaluated, presented experiments showing the microdroplet active mixing, and investigated the thermal effect of the created acoustic energy. © 2014 Elsevier B.V.

Butterworth J.A.,University of Colorado at Boulder | Pao L.Y.,University of Colorado at Boulder | Abramovitch D.Y.,Nanotechnology Group
Proceedings of the American Control Conference | Year: 2011

In previous work, we compared the raster tracking performance of two distinct combined feedforward/feedback control architectures while using model-inverse-based feedforward control [1], [2]. In this paper, we extend that work into the application of parallel and serial iterative learning control (ILC) architectures. These ILC architectures naturally relate to the two previously studied combined feedforward/feedback control architectures, feedforward closed-loop injection (FFCLI) and feedforward plant injection (FFPI). Experimental learning results from an atomic force microscope (AFM) raster scanner are provided as well as results comparing the FFPI and FFCLI architectures with those of the learned performance for parallel and series ILC. We show that the value of ILC over model-inverse-based feedforward methods is increased in the presence of model uncertainty or variation. © 2011 AACC American Automatic Control Council.

Home > Press > Multiple uses for the JPK NanoWizard AFM system in the Smart Interfaces in Environmental Nanotechnology Group at the University of Illinois at Urbana-Champaign Abstract: JPK Instruments, a world-leading manufacturer of nanoanalytic instrumentation for research in life sciences and soft matter, reports on the breadth of research applications where their NanoWizard® AFM system is being used in the Smart Interfaces in Environmental Nanotechnology Group under the leadership of Associate Professor, Rosa M Espinosa-Marzal. Dr Rosa M Espinosa-Marzal is an Associate Professor in the Department of Civil & Environmental Engineering at the University of Illinois at Urbana-Champaign. The goal of her research is to design innovative systems and improved materials that can solve environmental problems of our society by applying fundamentals of surface and colloidal science, materials chemistry, and nanotechnology. The central theme of her research group, Smart Interfaces in Environmental Nanotechnology (SIEN), is to design, synthesize, characterize and develop a fundamental understanding of bioinspired materials and of (bio) interfaces, also under nanoconfinement. Atomic force microscopy, AFM, is a vital tool for these studies. Speaking about her group and their experiences since the starting of their use of the JPK NanoWizard® AFM system, Dr Espinosa-Marzal says “My team of researchers is looking at a broad range of materials which require imaging in fluids to a high level resolution. The ability to measure low noise, high resolution force curves is of particular value as is the capability of working in liquid environments without the fear of damaging the piezo or sample. My students have made many positive comments which are important to me. I am confident that their imaging is of the quality they need to complete their research assignments.” Picking out some of the projects where the NanoWizard® is being successfully used, it is revealing to hear the comments of the SIEN group members describe what makes them particularly pleased with the performance of the system. In one project which is setting out to understand the structure of water at the interface with 2D materials such as graphene, the biggest challenge is to make high resolution, force spectroscopy measurements. Operating in liquid the NanoWizard® has produced high resolution phase images in AC mode that reveal the contamination on the graphene surface. Ultimately, the group hopes to study the layering of water molecules and ions on the graphene surface, which can be used as a possible interface for water purification. Imaging soft structures in aqueous environments is the challenge of the researchers developing model cell membranes. These are tri-layered soft structures, with interfacial and mechanical properties similar to a cell membrane. These require a low noise system to both image and perform nanomechanical characterization with QI™ mode of individual layers and the complete stratified structure. In a biofilm study, one researcher is looking to understand the precipitation of calcite in biofilms found in drinking water distribution systems. Here, colloidal AFM probes are applied to make surface force measurements on heterogeneous soft composites. These are used to determine mechanical forces of the films including adhesion and detachment forces. The combination of AFM with an inverted microscope has been invaluable here using JPK's patented Direct Overlay™ feature to identify appropriate areas to image and ultimately to generate force maps which allow the understanding of the spatial variability of the mechanical properties for mineralized and non-mineralized samples. Other projects include the study of biomineralization (imaging amorphous calcium carbonate) and how ionic liquids respond to nanoscale confinement and to surface heterogeneities. These just further illustrate the versatility of the JPK NanoWizard® in a multi-user research group. For more details about JPK's NanoWizard® AFM and their applications for the bio & nano sciences, please contact JPK on +49 30726243 500. Alternatively, please visit the web site: www.jpk.com or see more on Facebook: www.jpk.com/facebook and on You Tube: www.youtube.com/jpkinstruments. About JPK Instruments JPK Instruments AG is a world-leading manufacturer of nanoanalytic instruments - particularly atomic force microscope (AFM) systems and optical tweezers - for a broad range of applications reaching from soft matter physics to nano-optics, from surface chemistry to cell and molecular biology. From its earliest days applying atomic force microscope (AFM) technology, JPK has recognized the opportunities provided by nanotechnology for transforming life sciences and soft matter research. This focus has driven JPK's success in uniting the worlds of nanotechnology tools and life science applications by offering cutting-edge technology and unique applications expertise. Headquartered in Berlin and with direct operations in Dresden, Cambridge (UK), Singapore, Tokyo, Shanghai (China), Paris (France) and Carpinteria (USA), JPK maintains a global network of distributors and support centers and provides on the spot applications and service support to an ever-growing community of researchers. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

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