3,962 research outputs found
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Non-invasive investigations of a wall painting using optical coherence tomography and hyperspectral imaging
Multispectral and hyperspectral imaging are efficient methods of measuring spectral reflectance at high spatial resolution. This non-invasive technique has been applied to the imaging of paintings over the last 20 years. PRISMS (Portable Remote Imaging System for Multispectral Scanning) was designed specifically for imaging wall paintings. Optical Coherence Tomography (OCT) is a low coherence interferometric technique capable of fast non-invasive imaging of subsurface microstructure. This paper shows the first application of in situ OCT imaging of a wall painting. The combination of PRISMS and OCT gives information on the varnish and paint layer structure, pigment identification, the state of degradation of the paint and varnish layers and informing curators on the painting schemes and techniques
Microsystems technology: objectives
This contribution focuses on the objectives of microsystems technology (MST). The reason for this is two fold. First of all, it should explain what MST actually is. This question is often posed and a simple answer is lacking, as a consequence of the diversity of subjects that are perceived as MST. The second reason is that a map of the somewhat chaotic field of MST is needed to identify sub-territories, for which standardization in terms of system modules an interconnections is feasible. To define the objectives a pragmatic approach has been followed. From the literature a selection of topics has been chosen and collected that are perceived as belonging to the field of MST by a large community of workers in the field (more than 250 references). In this way an overview has been created with `applicationsÂż and `generic issuesÂż as the main characteristics
Implementing an SPM Controller with LabVIEW
The purpose of this article is to reduce the barrier of developing a house-made scanning probe microscope(SPM). Here in this paper,we cover all the details of programming an SPM controller with LabVIEW. The main controller has three major sequential portions. They are system initialization portion,scan control and image display portion and system shutdown portion. The most complicated and essential part of the main controller is the scan control and image display portion, which is achieved with various parallel tasks. These tasks are scan area and image size adjusting module, Y-axis scan control module, Xaxis scan and image transferring module, parameters readjusting module,emergency shutdown module,etc. A NI7831 RFPGA board is used to output the control signals and utilize the Z-axis real-time feedback controls.The system emergency shutdown is also carried out by the FPGA module. Receiving the shutdown command from the main controller,the FPGA board will move the probe to its XYZzero position, turn off all the high voltage control signals and also eliminate the possible oscillations in the system. Finally, how to operate the controller is also briefly introduced. That messy wires fly back and forth is the main drawback of LabVIEW programming. Especially when the program is complicated,this problem becomes more serious. We use a real example to show how to achieve complex functionalities with structural programming and parallel multi-task programming. The actual code showed in this paper is clear, intuitive and simple. Following the examples showed in this paper, readers are able to develop simple LabVIEW programs to achieve complex functionalities
IMP Science Gateway: from the Portal to the Hub of Virtual Experimental Labs in Materials Science
"Science gateway" (SG) ideology means a user-friendly intuitive interface
between scientists (or scientific communities) and different software
components + various distributed computing infrastructures (DCIs) (like grids,
clouds, clusters), where researchers can focus on their scientific goals and
less on peculiarities of software/DCI. "IMP Science Gateway Portal"
(http://scigate.imp.kiev.ua) for complex workflow management and integration of
distributed computing resources (like clusters, service grids, desktop grids,
clouds) is presented. It is created on the basis of WS-PGRADE and gUSE
technologies, where WS-PGRADE is designed for science workflow operation and
gUSE - for smooth integration of available resources for parallel and
distributed computing in various heterogeneous distributed computing
infrastructures (DCI). The typical scientific workflows with possible scenarios
of its preparation and usage are presented. Several typical use cases for these
science applications (scientific workflows) are considered for molecular
dynamics (MD) simulations of complex behavior of various nanostructures
(nanoindentation of graphene layers, defect system relaxation in metal
nanocrystals, thermal stability of boron nitride nanotubes, etc.). The user
experience is analyzed in the context of its practical applications for MD
simulations in materials science, physics and nanotechnologies with available
heterogeneous DCIs. In conclusion, the "science gateway" approach - workflow
manager (like WS-PGRADE) + DCI resources manager (like gUSE)- gives opportunity
to use the SG portal (like "IMP Science Gateway Portal") in a very promising
way, namely, as a hub of various virtual experimental labs (different software
components + various requirements to resources) in the context of its practical
MD applications in materials science, physics, chemistry, biology, and
nanotechnologies.Comment: 6 pages, 5 figures, 3 tables; 6th International Workshop on Science
Gateways, IWSG-2014 (Dublin, Ireland, 3-5 June, 2014). arXiv admin note:
substantial text overlap with arXiv:1404.545
Workshop on "Control issues in the micro / nano - world".
International audienceDuring the last decade, the need of systems with micro/nanometers accuracy and fast dynamics has been growing rapidly. Such systems occur in applications including 1) micromanipulation of biological cells, 2) micrassembly of MEMS/MOEMS, 3) micro/nanosensors for environmental monitoring, 4) nanometer resolution imaging and metrology (AFM and SEM). The scale and requirement of such systems present a number of challenges to the control system design that will be addressed in this workshop. Working in the micro/nano-world involves displacements from nanometers to tens of microns. Because of this precision requirement, environmental conditions such as temperature, humidity, vibration, could generate noise and disturbance that are in the same range as the displacements of interest. The so-called smart materials, e.g., piezoceramics, magnetostrictive, shape memory, electroactive polymer, have been used for actuation or sensing in the micro/nano-world. They allow high resolution positioning as compared to hinges based systems. However, these materials exhibit hysteresis nonlinearity, and in the case of piezoelectric materials, drifts (called creep) in response to constant inputs In the case of oscillating micro/nano-structures (cantilever, tube), these nonlinearities and vibrations strongly decrease their performances. Many MEMS and NEMS applications involve gripping, feeding, or sorting, operations, where sensor feedback is necessary for their execution. Sensors that are readily available, e.g., interferometer, triangulation laser, and machine vision, are bulky and expensive. Sensors that are compact in size and convenient for packaging, e.g., strain gage, piezoceramic charge sensor, etc., have limited performance or robustness. To account for these difficulties, new control oriented techniques are emerging, such as[d the combination of two or more âpackageable' sensors , the use of feedforward control technique which does not require sensors, and the use of robust controllers which account the sensor characteristics. The aim of this workshop is to provide a forum for specialists to present and overview the different approaches of control system design for the micro/nano-world and to initiate collaborations and joint projects
THE DEVELOPMENT OF A NOVEL ELECTRO-MAGNETIC FORCE MICROSCOPE
This thesis describes the development of a new type of Magnetic Force Microscope
(MFM) probe based on a unique electromagnetic design. In addition the design,
construction and testing of a new MFM system, complete in both hardware and software, is
also described. The MFM allowed initial tests on prototypes of the new probe, and is to
provide a base for future new probe integration. The microscope uses standard MFM
micro-cantilever probes in static modes of imaging. A new computer hosted DSP control
system, software, and its various interfaces with the MFM have been integrated into the
system. The system has been tested using standard probes with various specimens and
satisfactory results have been produced.
A novel probe has been designed to replace the standard MFM magnetic coated tip with a
field generated about a sub-micron aperture in a conducting film. The field from the new
probe is modelled and its imaging capability investigated, with iterative designs analysed
in this way. The practical construction and potential problems therein, of the probe are
also considered. Test apertures have been manufactured, and an image of the field
produced when operating is provided as support to the theoretical designs. Future methods
of using the new probe are also discussed, including the examination of the probe as a
magnetic write mechanism.
This probe, integrated into the MFM, can provide a new method of microscopic magnetic
imaging, and in addition opens a new potential method of magnetic storage that will
require further research
Fast pixelated detectors in scanning transmission electron microscopy. Part II: post acquisition data processing, visualisation, and structural characterisation
Fast pixelated detectors incorporating direct electron detection (DED)
technology are increasingly being regarded as universal detectors for scanning
transmission electron microscopy (STEM), capable of imaging under multiple
modes of operation. However, several issues remain around the post acquisition
processing and visualisation of the often very large multidimensional STEM
datasets produced by them. We discuss these issues and present open source
software libraries to enable efficient processing and visualisation of such
datasets. Throughout, we provide examples of the analysis methodologies
presented, utilising data from a 256Ă256 pixel Medipix3 hybrid DED
detector, with a particular focus on the STEM characterisation of the
structural properties of materials. These include the techniques of virtual
detector imaging; higher order Laue zone analysis; nanobeam electron
diffraction; and scanning precession electron diffraction. In the latter, we
demonstrate nanoscale lattice parameter mapping with a fractional precision
â€6Ă10â4 (0.06%)
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Rapid manufacturing as a tool for agile manufacturing: applications and implementation perspectives
Manufacturing engineers and technologists around the globe are already well familiar with manufacturing methodologies and systems developments in the last part of the twentieth century. Many are probably also familiar with the current state of Rapid Prototyping (RP) technologies, especially in the areas of concept model making and prototype development. They may not however, be so familiar with the more recent developments of these technologies towards Rapid Manufacturing (RM) and the directions which the applications of RM technologies are taking for agile manufacturing purposes in particular. This paper critically reviews the various technologies currently available, outlines development trends in RM, discusses the approach, application and implementation perspectives by which these RM technologies are applied for increasing agility and responsiveness in manufacturing. Furthermore, the paper describes two case study examples to further illustrate the application scenarios in agile manufacturing before concluding remarks
Barrier Dynamics of Nuclear Pore Complexes and Biomimetic Nanopores
Nuclear pore complexes (NPCs) mediate macromolecular traffic between the cytoplasm and the nucleus in eukaryotic cells. Tethered within each ~60 nm-diameter NPC lie numerous intrinsically disordered proteins that bear phenylalanine-glycine (FG) repeats known as FG nucleoporins (FG Nups). The FG Nups establish a selective barrier that impedes the passage of non-specific cargoes but rapidly yields to cargo-carrying transport receptors. However, the basic functional form of the FG Nups remains unresolved with respect to their spatiotemporal behaviour inside native NPCs. Here, we use high-speed atomic force microscopy (HS-AFM) to visualize nanoscopic FG Nup behaviour inside Xenopus laevis oocyte NPCs at near transport-relevant timescales. Our results show that the NPC channel is circumscribed by highly flexible, dynamically fluctuating FG Nups that elongate and retract in a stochastic manner consistent with the diffusive motion of tethered polypeptide chains. On this basis, extended FG Nups can momentarily interlink or coalesce into short-lived metastable condensates in the central channel, but do not cohere into a static meshwork that spans the entire pore. By resolving the time-dependent behaviour of FG Nups in the NPC, our findings bring consensus to barrier models that mainly disagree on static interpretations of how the FG Nups are spatially arranged in the pore. Furthermore, HS-AFM has been used to study the behavior of polyethylene glycol (PEG) polymer chains tethered inside of artificial nanopores. Our data shows that longer PEG chains serve are more effective in forming a barrier in pore than short PEG polymers. This serves as a strategy to design bio-mimetic nanopores with NPC-like functionality in the future
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