MEMS Technology for Biomedical Imaging Applications

Biomedical imaging is the key technique and process to create informative images of the human body or other organic structures for clinical purposes or medical science. Micro-electro-mechanical systems (MEMS) technology has demonstrated enormous potential in biomedical imaging applications due to its outstanding advantages of, for instance, miniaturization, high speed, higher resolution, and convenience of batch fabrication. There are many advancements and breakthroughs developing in the academic community, and there are a few challenges raised accordingly upon the designs, structures, fabrication, integration, and applications of MEMS for all kinds of biomedical imaging. This Special Issue aims to collate and showcase research papers, short commutations, perspectives, and insightful review articles from esteemed colleagues that demonstrate: (1) original works on the topic of MEMS components or devices based on various kinds of mechanisms for biomedical imaging; and (2) new developments and potentials of applying MEMS technology of any kind in biomedical imaging. The objective of this special session is to provide insightful information regarding the technological advancements for the researchers in the community

An investigation of the conductivity of peptide nanostructured hydrogels via molecular self-assembly

Nanoscale, conductive wires fabricated from organic molecules have attracted considerable attention in recent years due to their anticipated applications in the next generation of optical and electronic devices. Such highly ordered 1D nanostructures could be made from a number of routes. One route of particular interest is to self-assemble the wires from biomolecules due to the wide range of assembly methods that can be adapted from nature. For example, biomolecules with aromatic motifs can be self-assembled so that good π-π stacking is achieved in the resultant nanostructure. An additional advantage of using biomolecules is that it enables the interface of the electronic materials with biological systems, which is important for many applications, including nerve cell communication and artificial photosynthesis. In this study, nanowires were prepared by the molecular self-assembly of oligopeptides that were coupled to aromatic components. In order to achieve charge transport though the nanowires, it was imperative that the aromatic components were arranged so that there was π-π stacking with very few structural defects. Therefore, enzymes were used to control the formation of the hydogelators which subsequently self-assembled to produce nanowire networks. Two main systems were studied in this thesis.In the first system, hydrogelators were produced from aromatic peptide amphiphiles via the enzymatic hydrolysis of the methyl ester of fluorenylmethoxycarbonyl (Fmoc)-di/tripeptides. These hydrogelators formed nanostructures due to π-π stacking between the Fmoc groups and H-bonding between the peptides. The nanostructures in turn produced macroscale gel networks. The nanostructures were analyzed by wide angle X-ray diffraction and fluorescence spectroscopy. A combination of Fourier transform infra-red (FTIR), Transmission Electron Microscopy (TEM), Cryo-TEM, and Atomic Force Microscopy (AFM) was used to characterize the networks. The charge transport properties of the dried networks were studied using impedance spectroscopy. Fmoc-L₃ was found to assemble into nanotubes whose walls consisted of 3 self-assembled layers and possessed inner and outer diameters of ~ 9 nm and ~ 18 nm, respectively. The Fmoc-L₃ networks were structurally stabile and were electronically conductive under a vacuum. The sheet resistance of the peptide networks increased with relative humidity due to the increasing ionic conductivity. The resistance of the networks was 0.1 MΩ/sq in air and 500 MΩ/sq in vacuum (pressure: 1.03 mbar) at room temperature. The networks had a band gap of between 1 to 4 eV as measured by UV-Vis spectroscopy and the temperature-impedance studies. Possible routes for aligning the Fmoc-L3 networks were studied in an attempt to improve their conductivity in one direction. In particular, the peptides were assembled under an electric field (0 to 3.75 kV/cm). Random networks were produced at low field strengths, whereas a degree of alignment was obtained at a field strength of 3.75 kV/cm. The conductivity of the aligned networks in the direction of alignment was a factor of three times higher than that of the random networks.The second system studied was Fmoc-dipeptide-OMe hydrogels produced by the enzymatic condensation of an Fmoc-amino acid and an amino acid ester. Preliminary results found that Fmoc-SF-OMe assembled into nanosheets, nanoribbons and spherulites, depending on the temperature at which self-assembly occurred. The Fmoc-XY-OMe films possessed an extremely high resistance (1012 Ω).EThOS - Electronic Theses Online ServiceRein UlijnGBUnited Kingdo

Earth Observatory Satellite system definition study. Report 3: Design cost trade-off studies and recommendations

An analysis of the design and cost tradeoff aspects of the Earth Observatory Satellite (EOS) development is presented. The design/cost factors that affect a series of mission/system level concepts are discussed. The subjects considered are as follows: (1) spacecraft subsystem cost tradeoffs, (2) ground system cost tradeoffs, and (3) program cost summary. Tables of data are provided to summarize the results of the analyses. Illustrations of the various spacecraft configurations are included

Process based Modelling of Chemical and Physical Aerosol Properties Relevant for Climate and Health

Atmospheric aerosol particles have substantial influence on climate and air quality. However, the anthropogenic influence on the atmospheric aerosol is still poorly known. This limits the understanding of past and future climate changes. Additionally, both epidemiological and toxicological studies indicate adverse health effects of inhaled aerosol particles. In order to study the effect of atmospheric processes on the particle properties relevant for climate and health, two models were developed and implemented. The first is a 2D-Lagrangian model for Aerosol Dynamics, gas phase CHEMistry and radiative transfer (ADCHEM), which treats the dispersion in the vertical and horizontal direction perpendicular to air mass trajectories. The second model is a kinetic multilayer model for Aerosol Dynamics, gas and particle phase chemistry in laboratory CHAMber environments (ADCHAM). With ADCHAM it is possible to study process based formation and evaporation of secondary organic aerosol particles, and mass transfer limitations and reactions within the particle phase. ADCHEM was used to quantify the anthropogenic influence from the city of Malmö (280 000 inhabitants) in southern Sweden. In Malmö and a few tens of kilometres downwind, the primary particle emissions have a large influence on the particle number concentration. However, more than 2 hours downwind Malmö, the anthropogenic particle mass contribution is dominated by secondary ammonium nitrate. To quantify the direct and indirect climate impact of urban aerosol emissions, the secondary aerosol formation which changes the optical and hygroscopic properties of the primary soot particles, needs to be addressed in future measurements and process modelling. ADCHAM was used to simulate different laboratory chamber experiment, with focus on potential influential but poorly known processes for secondary organic aerosol properties, formation and evaporation rates in the atmosphere (i.e. oligomerization, organic salt formation, salting-out effects, oxidation of organic compounds in the particle phase and mass transfer limitations in the particle phase). The model results reveal that formation of small amounts of low-volatile and long lived oligomers, which accumulate in the particle surface layers, can effectively prevent the evaporation of more volatile compounds. This can significantly prolong the lifetime of SOA in the atmosphere

Novel enhancement of HVOF thermal sprayed nanostructured WC-12Co / inconel-625 coatings for tribocorrosion applications

The HVOF thermal spray process is gradually becoming one of the leading coating techniques taking over traditional electrolytic chrome plating (EHC) due to EHCs harmful effects on the human body. Despite the high quality coatings produced by the HVOF thermal spray system, its role has yet to be validated in the replacement of other traditional coating techniques where specific surface properties are required in particular service operation. Obstacles associated with high-velocity oxy-fuel (HVOF) thermal spray significantly affect coating performance, especially in erosion and corrosion preventive applications. The coating layer therefore must be enhanced with a view to reducing microstructural defects and thereby prolonging the coating’s service life. This research is aimed at examining the effect of using a CO2 laser system as a post-heat treatment and enhancement procedure applied to two coatings types investigated in this research that were deposited by an HVOF thermally sprayed process onto carbon steel 4041 substrates: firstly, 100% tungsten carbide cobalt (nano-structured) WC-12Co (InfralloyTM S7412) and secondly, WC-12Co nanostructured powder mixed with a nickel chromium alloy (Diamalloy 1005- Inconel 625) at an optimised weight percentage composition of 75% and 25% respectively. The work was carried out through the introduction of experimentally based mathematical models developed by applying response surface methodology (RSM) through Box-Behnken design (BBD), based on three levels of each factor selected, namely laser power, scanning speed and focal position/beam size, using Design of Expert software related to the coating’s erosion resistance, melt-pool geometry, mechanical properties and operating cost of the laser treatment. Furthermore, the desirability optimisation approach, based on two criteria (quality and cost), was used for both coatings in conjunction with RSM to determine the optimal combination of the laser parameters to achieve the required laser-treated coating desirability. Different outcomes of surface properties were achieved by varying the laser-processing parameters. The results demonstrate that significant improvement in coating erosion wear (dry and slurry erosion) and mechanical properties (bending strength, surface roughness and microhardness), compared to as-sprayed coating, was achieved after laser treatment in both coating types, especially the singular nanostructured WC-12Co coating. The optimal laser settings found in the quality criteria are 350 W, 37.24 mm and 150.00 mm/min for laser power, focal position and scanning speed, respectively, for the monomial nWC-12Co coating and 350 W, 45 mm and 300 mm/min for the cost criteria. To the same extent, the optimal setting for the mixed coating for the quality criteria are 169 W, 35 mm and 257.4 mm/min and 250 W, 45 mm and 300 mm/min for the cost criterion. The optimal laser setting mentioned in the quality criteria for the erosive wear, for example, saw an approximately five- to seven-fold reduction in mass loss for dry and slurry erosion in comparison to the untreated monomial nWC-12Co coating. The latter setting created an approximately 7-fold reduction in mass losses for the dry erosion and a 27% reduction in mass losses for slurry erosion compared to their untreated counterparts. This can mainly be ascribed to the elimination of the discrete splat structure, porosity and microcrevice, as well as the enhanced homogeneity of the nano-scale WC hard ceramic distribution across the metal matrix. Less improvement was seen for the mixed coating as a result of high energy fluence (J/mm2); the coating surface became rough and gas pockets started forming within the melted zones, creating a porous coating layer that had a negative impact on coating bending strength and erosion performance. Moreover, the results indicate a strong correlation between irradiance and residence time of the laser processing, along with coating composition, with respect to the melt-pool dimensions. Finally, based on the enhancement achieved in the coating properties under the optimal laser settings for both coatings, compared to the untreated ones, the results prove that laser post processing is a cost-effective procedure (approximately 17% or less of that of HVOF) and therefore will markedly extend the service life of both coatings, saving a lot of money that would be wasted in the case of the untreated ones

Simulation of Flat Surface Modle Film Cooling Enhancement with Different Injection Orientation

The cooling effectiveness of combustor transition pieces increases significantly in accordance with turbine temperature. In this issue, we create a scenario in which using three-dimensional computational to predict the performance of film cooling model with three rows holes and double chambers on the flat surface that the model could simulate the TPâ??s structure and performance. Fluent, a commercial CFD software, is extensively used in the current work for numerical simulations. A comprehensive study is performed on the effect of coolant injection angles on film cooling. The the temperature distribution in the inner wall, cooling effectiveness, and the velocity distribution of coolant flow with different cases is compared. Analysis on flow injection orientations is beneficial to enhance the turbine inlet temperature and improve gas turbine efficienc

Nanofibers - production, properties and functional applications

With the rapid development of nanoscience and nanotechnology over the last decades, great progress has been made not only in the preparation and characterization of nanomaterials, but also in their functional applications. As an important one-dimensional nanomaterial, nanofibers have extremely high specific surface area because of their small diameters, and nanofiber membranes are highly porous with excellent pore interconnectivity. These unique characteristics plus the functionalities from the materials themselves impart nanofibers with a number of novel properties for applications in areas as various as biomedical engineering, wound healing, drug delivery and release control, catalyst and enzyme carriers, filtration, environment protection, composite reinforcement, sensors, optics, energy harvest and storage , and many others. More and more emphasis has recently been placed on large-scale nanofiber production, the key technology to the wide usages of nanofibers in practice. Tremendous efforts have been made on producing nanofibers from special materials. Concerns have been raised to the safety issue of nanofibrous materials. This book is a compilation of contributions made by experts who specialize in their chosen field. It is grouped into three sections composed of twenty-one chapters, providing an up-to-date coverage of nanofiber preparation, properties and functional applications. I am deeply appreciative of all the authors and have no doubt that their contribution will be a useful resource of anyone associated with the discipline of nanofibers

An aesthetic for sustainable interactions in product-service systems?

Copyright @ 2012 Greenleaf PublishingEco-efficient Product-Service System (PSS) innovations represent a promising approach to sustainability. However the application of this concept is still very limited because its implementation and diffusion is hindered by several barriers (cultural, corporate and regulative ones). The paper investigates the barriers that affect the attractiveness and acceptation of eco-efficient PSS alternatives, and opens the debate on the aesthetic of eco-efficient PSS, and the way in which aesthetic could enhance some specific inner qualities of this kinds of innovations. Integrating insights from semiotics, the paper outlines some first research hypothesis on how the aesthetic elements of an eco-efficient PSS could facilitate user attraction, acceptation and satisfaction