Accurate quantification of the hydrophobic/hydrophilic properties of protein surfaces requires detailed knowledge of the hydrophobicity of amino acids at the atomic level. As discussed previously in various published papers, molecular modeling can be used with effect to acquire such knowledge. In this study, molecular dynamics methods have been employed to examine the role of the distance between an amino acid atom and its nearest water molecule in relation to its intrinsic atom hydrophobicity. This distance is the radius of the water-excluding-region around the atom; therefore, it can provide information on the solvent accessibility and steric hindrance that may influence the atom hydrophobicity. Molecular models of tripeptide in the form of GXG, and pentapeptides in the form of AcWLXLL-NH₂ and AcGGXGGNH₂ for 20 natural amino acids in the X position were constructed and allowed to dynamically interact with surrounding water for a sufficient period of time. The distance value for each atom in all natural amino acids were calculated and analyzed against the atom/amino acid's other parameters such as radial distribution function, solvent-accessible surface area, and hydrogen bonding. It was observed that, when the dynamic factor is taken into account, peptide molecular conformation is modified noticeably with residue type. For protein surface identification purposes, preliminary results are consistent with those reported in the literature on the need to include the amino acid structural properties as well as the effects of its neighboring residues. Further investigation is envisaged in order to verify these observations.

Protein adsorption at solid-liquid interfaces is critical to many applications, including biomaterials, protein microarrays and lab-on-a-chip devices. Despite this general interest, and a large amount of research in the last half a century, protein adsorption cannot be predicted with an engineering level, design-orientated accuracy. Here we describe a Biomolecular Adsorption Database (BAD), freely available online, which archives the published protein adsorption data. Piecewise linear regression with breakpoint applied to the data in the BAD suggests that the input variables to protein adsorption, i.e., protein concentration in solution; protein descriptors derived from primary structure (number of residues, protein hydrophobicity and spread of amino acid hydrophobicity, isoelectric point); surface descriptors (contact angle); and fluid environment descriptors (pH, ionic strength), correlate well with the output variable - the protein concentration on the surface. Furthermore, neural network analysis revealed that the size of the BAD makes it sufficiently representative, with a neural network-based predictive error of 5% or less. Interestingly, a consistently better fit is obtained if the BAD is divided into two separate subsets representing protein adsorption on hydrophilic and hydrophobic surfaces. Based on these findings, selected entries from the BAD have been used to construct neural network-based estimation routines, which predict the amount of adsorbed protein, the thickness of the absorbed layer and the surface tension of the proteincovered surface. While the BAD is of general interest, the prediction of the thickness and the surface tension of the protein-covered layers are of particular relevance to the design of microfluidics devices.

Wirelessly interrogated bio-MEMS devices are becoming more popular due to many challenges, such as improving the diagnosis, monitoring, and patient wellbeing. The authors present here a passive, low power and small area device, which can be interrogated wirelessly using a uniquely coded signal for a secure and reliable operation. The proposed new approach relies on converting the interrogating coded signal to surface acoustic wave that is then correlated with an embedded code. The suggested method is implemented to operate a micropump, which consist of a specially designed corrugated microdiaphragm to modulate the fluid flow in microchannels. Finite Element Analysis of the micropump operation is presented and a performance was analysed. Design parameters of the diaphragm design were finetuned for optimal performance and different polymer based materials were used in various parts of the micropump to allow for better flexibility and high reliability.

This paper describes the design, simulation, fabrication and experimental analysis of a passive micromixer for the mixing of biological solvents. The mixer consists of a T-junction, followed by a serpentine microchannel. The serpentine has three arcs, each equipped with circular barriers that are patterned as two opposing triangles. The barriers are engineered to induce periodic perturbations in the flow field and enhance the mixing. CFD (Computational Fluid Dynamics) method is applied to optimise the geometric variables of the mixer before fabrication. The mixer is made from PDMS (Polydimethylsiloxane) using photo- and soft-lithography techniques. Experimental measurements are performed using yellow and blue food dyes as the mixing fluids. The mixing is measured by analysing the composition of the flow's colour across the outlet channel. The performance of the mixer is examined in a wide range of flow rates from 0.5 to 10 μl/min. Mixing efficiencies of higher than 99.4% are obtained in the experiments confirming the results of numerical simulations. The proposed mixer can be employed as a part of lab-on-a-chip for biomedical applications.

In this work, we have investigated the effect of nanostructured surfaces on the attachment and viability of two bacterial species of medical relevance. Surfaces having squares, channels and dots in the nano size range with intermittent hydrophobicity and hydrophilicity showed complex effects on both live and dead E. coli cells. Nevertheless the behaviour of S. aureus was found to be less modulated by the surface properties. The square structures had promising repellent effect on both live and dead E. coli species while S. aureus populated these surfaces very well. On dot nanostructures the population by E. coli was considerably higher than on the surrounding spaces while the distribution of S. aureus cells remained uniform on both structured and unstructured areas. When the bacteria were applied to surfaces with channels, live E. coli cells showed a very interesting fluctuation in function depending on the width of the channels but this fluctuation was not observed in case of dead cells. Because of its spherical form, lacking flagellae and production of extracellular substances, S. aureus adhered to this structure more evenly and no fluctuation was observed. Strain specific bacterial physiology and reactivity to these surfaces may possibly also be a factor in influencing the interaction. These initial results contribute to the purposeful design of species-specific pro- or anti-bacterial surfaces for the use of lab-on-a-chip devices and various types of medical devices.

Self-assembling polymers have recently attracted significant scientific interest, since they spontaneously generate highly ordered structures with high resolution precision, and provide simple, parallel, and cost-effective processes for nanofabrication. Such systems can be achieved with block copolymers which, when produced as thin films, offer great potential as lithographic templates for the fabrication of photonic band-gap materials, ultrahigh-density nanodots or nanowire arrays, memory and capacitor devices, and nano-patterned substrates for biosensors. Although self-assembling block copolymers can form a variety of surface topographies at the nm scale, like spheres, cylinders, and lamellae, their structural steering through the annealing conditions has in many cases not been fully investigated. In the present investigation optimum production conditions for the preparation of nanostructures from poly(styrene)-block-poly(MMA) diblock copolymers have been established to enable the production of surfaces as thin films (<40 nm) on spin-coated silicon wafers either with parallel cylindrical structures or with vertical cylinders. The resulting self-assembling structures were then evaluated by atomic force microscopy. The obtained nanostructured polymers were then incubated with two microbial species, the gram negative E. coli and the gram positive S. aureus to assess their behaviour. The patterns of the thin film surfaces affected the bacterial attachment. Such self assembly processes can be used to create surfaces acting as bacterial attractants or repellents.

Atomic force microscopy (AFM) in conjunction with cross-section analysis was applied to determine the distribution, position and contact angle of spray-deposited water micro-droplets on micro-structured arrays. For this investigation, two micro-structured arrays on silicon wafers with a chessboard pattern of depressions and protrusions of various sizes were manufactured by e-beam lithography. The first array had a silicon oxide/silicon structure (hydrophilic/hydrophilic) with an elevated silicon oxide layer of 40 nm and the second had a gold/silicon structure (hydrophobic/hydrophilic) with an elevated gold layer of 35 nm. On the first array with only hydrophilic surfaces, the behavior of the water droplets was mainly affected by topography, whereby the contact angles on the structures were considerably higher than the contact angles of droplets on unstructured reference surfaces. On the second array the water micro-droplets were confined in the hydrophilic depressions by the hydrophobic boundary whereby the highest contact angle was measured on the smallest squares and the lowest contact angle was found on the largest μm exceeding the contact angles of the droplets on the unstructured reference materials.

The medical devices such as a micropump to extract blood through a tube have a structure which needle and pump part are mutually separated. Therefore, it is not easy to make smaller than the conventional pump. In this research, we aim to develop the pump combined with a tube as a final purpose. In this study, ring type PZT elements are mounted on the surface of the silicone tube, and the stationary waves are generated in the tube by the vibration of those PZT on the tube verified by changing the AC voltage. The waves generated by the collision of large and small stationary waves are synthesized, and then the wave becomes a progressive wave with an elliptic motion in the tube. The flow function demonstrated by the tube type micropump was evaluated and the flow velocities were increased 2.78% and decreased 1.79%. On the other hand, we have a technique to produce a titanium microtube by using RF magnetron sputtering deposition technique. A Titanium micro tube with the size of a female mosquito's labium (60µm external and 25μm internal diameter) was produced by the sputter deposition method. In order to deposit PZT thin film on the titanium micro tube, the thin film process is used. The thin film deposition conditions of the PZT thin film are investigated and the characteristic of the PZT thin films are evaluated.

Classical multi-(two-)dimensional separations in gas chromatography (GC) require switching systems to transfer the gas flow stream from the first to second dimension. This can be accomplished by valve systems, but is more suitably effected by pressure balanced systems, such as the Deans' switch method. Recent developments in microfluidics and related micro-technologies should make gas phase switching much more effective. The capillary flow technology platform of Agilent Technologies is an example of recent developments introduced to GC. Thus various Deans' switch pressure balanced devices, stream splitters, and column couplings bring new capabilities to analytical GC. We are uniquely placed to take advantage of the new devices, owing to our development of advanced operational methods in GC which can make use of microfluidic capillary couplings, and novel cryogenic approaches that deliver performance previously impossible with conventional methods. Multidimensional chromatographic flow switching to isolate pure compounds from complex mixtures suggests many potential applications for enhanced chemical analysis. Multiple dimensions of GC analysis, capabilities for integrating different spectroscopic detection methods for chemical identification of isolated chemical species including mass spectrometry, nuclear magnetic resonance and Fourier transform infrared, can be proposed. Applications in the essential oils and petrochemical area will be outlined.

Microfluidics has the potential to enhance the understanding of the of biological fluids under strain, due to the laminar nature of the fluid and the possibility to mimic the real conditions. We present advances on characterization of a microfluidic platform to study high strain rate flows in the transport of biological fluids. These advances are improvements on the reproduction of a constant extensional strain rate using micro contractions and development of 3D numerical models. The micro geometries have been fabricated in polydimethyl siloxane (PDMS) using standard soft-lithography techniques with a photolithographically patterned mold. A comparison of some microcontractions with different funnel characteristics is presented. The Micro Particle Image Velocimetry technique has been applied to validate the numerical simulations. We demonstrate the use of microfluidics in the reproduction of a large range of controllable extensional strains that can be used in the study of the effect of flow on biological fluids.

A microfluidic system for cancer diagnosis based around a core MEMS biosensor technology is presented in this paper. The principle of the MEMS biosensor is introduced and the functionalisation strategy for cancer marker recognition is described. In addition, the successful packaging and integration of functional MEMS biosensor devices are reported herein. This ongoing work represents one of the first hybrid systems to integrate a PCB packaged silicon MEMS device into a disposable microfluidic cartridge.

Microbubbles have been used as ultrasound contrast agents in medical applications such as imaging, and also for drug/gene delivery, target destruction and so on. Microbubbles are normally made by sonication techniques and the resulting size distribution is very large. Microfluidics provides an alternative way of microbubble fabrication due to recent advances in microfabrication and microfluidics development. The current techniques are capable of making bubbles with a size of several micrometers. However, the throughput for such a size range is very limited. In this study, a new microfluidic bubble generation chip was developed, which incorporates a T-junction PDMS microchannel network with an inserted glass capillary. The flow rate of liquid, gas pressure and the inserted capillary inner diameter are crucial for control of the bubble size. A series of capillaries with different inner diameters have been used. With co-flow focusing liquids and a fine-drawn glass capillary, bubble size could be decreased and bubbles with a size of 13 μm in diameter were generated reliably after the optimizing of liquid flow rate and gas pressure. It was found that a 5 μm capillary inserted microchip produced 11 μm diameter bubbles with a cross-flow rupturing method.

The combined use of film transparency masks and dry film resist has allowed a rapid prototyping of designs and structures in chips for droplet generation. Patterning of the film resist has produced channels with smooth vertical sidewalls. The minimum feature dimension, δ, was reduced by increasing the resolution and spacing of the pattern geometries in the film mask. For a single layer of resist (~35 μm thick), a minimum feature width of ~60 μm was obtained using 2040 dpi transparency masks, 40 µm for 5800 dpi transparency masks and 25 μm using a Cr mask of equal size/ spacing of features. A doubling of the spacing between features in a 2400 dpi masks resulted in an attainable feature size of ~40 μm. The minimum feature dimension increased exponentially with thickness of 5038 resist. Microfluidic chips which were fabricated in PMMA by this method have demonstrated controlled characteristics in the generation of oil droplets in water.

Biological fluids such as blood, proteins and DNA solutions moving within fluidic channels can potentially be exposed to high level of shear, extension or mixed stress, either in vitro such as industrial processing of blood products or in vivo such as ocurrs in some pathological conditions. This exposure to a high level of strain can trigger some reactions. In most of the cases the nature of the flow is mixed with shear and extensional components. The ability to isolate the effects of each component is critical in order to understand the mechanisms behind the reactions and potentially prevent them. Applying hydrodynamic flow focusing, we present in this investigation the characterization of microchannels that allow study of the regions of high shear or high extension strain rate. Micro channels were fabricated in polydimethyl siloxane (PDMS) using standard soft-lithography techniques with a photolithographically patterned mold. Characterization of the regions with high shear and high extension strain rate is presented. Computational Fluid Dynamics (CFD) simulations in three dimensions have been carried out to gain more detailed local flow information, and the results have been validated experimentally. A comparison between the numerical models and experiment and is presented. The advantages of microfluidic flow focusing in the study of the effects of shear and extension strain rates for biological fluids are outlined.

The paper presented an enhancement solution for transdermal drug delivery using microneedles array with biodegradable tips. The microneedles array was fabricated by using deep reactive ion etching (DRIE) and the biodegradable tips were made to be porous by electrochemical etching process. The porous silicon microneedle tips can greatly enhance the transdermal drug delivery in a minimum invasion, painless, and convenient manner, at the same time; they are breakable and biodegradable. Basically, the main problem of the silicon microneedles consists of broken microneedles tips during the insertion. The solution proposed is to fabricate the microneedle tip from a biodegradable material - porous silicon. The silicon microneedles are fabricated using DRIE notching effect of reflected charges on mask. The process overcomes the difficulty in the undercut control of the tips during the classical isotropic silicon etching process. When the silicon tips were formed, the porous tips were then generated using a classical electrochemical anodization process in MeCN/HF/H₂O solution. The paper presents the experimental results of in vitro release of calcein and BSA with animal skins using a microneedle array with biodegradable tips. Compared to the transdermal drug delivery without any enhancer, the microneedle array had presented significant enhancement of drug release.

Determining the lactose concentration in human breast milk (HBM) via standard assay techniques requires fat removal from the milk (defatting), followed by lactose detection in the remaining skim milk. This work focuses on methods of defatting which can be subsequently integrated in the same Lab-on-Chip (LOC) as the lactose measurement. One method under study for defatting HBM is the use of a cross-flow microfiltration structure. This kind of microfiltration prevents clogging and separates the large fat globules from the smaller nutrition constituents of milk, of which lactose is amongst the smallest. To test if large fat globules may clog the channel or not, the biocompatibility of PMMA and HBM was studied. The weight of absorbed fat on the surface of PMMA was found to be 3-orders of magnitude lower than that of the total fat in HBM. Photolithgraphy using SU-8 was applied for mold fabrication; however, hot-embossing using SU-8 mold has not been successful due to the high stress resulting in the demolding process. To improve mold strength, nickel molds were fabricated by electroplating using different current densities. As expected, the deposition rates were found to have a linear relationship with applied current density, while the smaller features have a higher deposition rate than larger features.

Glaucoma is a common cause of blindness. Wireless, continuous monitoring of intraocular pressure (IOP) is an important, unsolved goal in managing glaucoma. An IOP monitoring system incorporated into a glaucoma drainage implant (GDI) overcomes the design complexity associated with incorporating a similar system in a more confined space within the eye. The device consists of a micro-electro-mechanical systems (MEMS) based capacitive pressure sensor integrated with an inductor printed directly onto a polyimide printed circuit board (PCB). The device is designed to be incorporated onto the external plate of a therapeutic GDI. The resonance frequency changes as a function of IOP, and is tracked remotely using a spectrum analyzer. A theoretical model for the reader antenna was developed to enable maximal inductive coupling with the IOP sensor implant. Pressure chamber tests indicate that the sensor implant has adequate sensitivity in the IOP range with excellent reproducibility over time. Additionally, we show that sensor sensitivity does not change significantly after encapsulation with polydimethylsiloxane (PDMS) to protect the device from fluid environment. In vitro experiments showed that the signal measured wirelessly through sheep corneal and scleral tissue was adequate indicating potential for using the system in human subjects.

During hemanalysis, it is necessary to separate blood cells from whole blood. Many blood separation methods, for example, centrifugation and filtering, are in practical use. However, the use of these methods involves problems from the perspectives of processing speed and processing volume. We develop new types of blood separation devices that use piezo-ceramic vibrators. The first device uses a capillary. One end of the capillary is fixed to the device frame, and the other is fixed to a piezo-ceramic vibrator. The vibrator transmits bending waves to the capillary. This device can process only a small amount of solution; therefore, it is not suitable for hemanalysis. In order to solve this problem, we developed a second device; this device has a pair of thin glass plates with a small gap as a substitute for the capillary used in the first device. These devices are based on the fact that particles heavier than water move toward transverse velocity antinodes while those lighter than water move toward velocity nodes. In this report, we demonstrate the highspeed separation of silica microbeads and 50-vol% glycerol water by using these devices. The first device can separate the abovementioned solution within 3 min while the second can separate it within 1 min. Both devices are driven by a rectangular wave of 15 to 20 Vpp. Furthermore, it has been confirmed that red blood cells are separated from diluted whole blood using the first device within approximately 1 min. These devices have transparency, so they can compose as the analysis system with the chemical analyzer easily.

This paper reports on the development of a hand-held device for on-site detection of organophosphonate nerve agent degradation products. This field-deployable analyzer relies on efficient microchip electrophoresis separation of alkyl methylphosphonic acids and their sensitive contactless conductivity detection. Miniaturized, low-powered design is coupled with promising analytical performance for separating the breakdown products of chemical warfare agents such as Soman, Sarin and VX . The detector has a detection limit of about 10 μg/mL and has a good linear response in the range 10-300 μg/mL concentration range. Applicability to environmental samples is demonstrated .The new hand-held analyzer offers great promise for converting conventional ion chromatography or capillary electrophoresis sophisticated systems into a portable forensic laboratory for faster, simpler and more reliable on-site screening.

Pulmonary drug delivery transports the drug formulations directly to the respiratory tract in the form of inhaled particles or droplets. Because of the direct target treatment, it has significant advantages in the treatment of respiratory diseases, for example asthma. However, it is difficult to produce monodispersed particles/droplets in the 1-10 micron range, which is necessary for deposition in the targeted lung area or lower respiratory airways, in a controllable fashion. We demonstrate the use of surface acoustic waves (SAWs) as an efficient method for the generation of monodispersed micron dimension aerosols for the treatment of asthma. SAWs are ten nanometer order amplitude electroacoustic waves generated by applying an oscillating electric field to an interdigital transducer patterned on a piezoelectric substrate. The acoustic energy in the waves induces atomization of the working fluid, which contains a model drug, albuterol. Laser diffraction techniques employed to characterize the aerosols revealed mean diameter of the aerosol was around 3-4 μm. Parallel experiments employing a one-stage (glass) twin impinger as a lung model demonstrated a nearly 80% of atomized drug aerosol was deposited in the lung. The aerosol size distribution is relatively independent of the SAW frequency, which is consistent with our predictive scaling theory which accounts for the dominant balance between viscous and capillary stresses. Moreover, only 1-3 W powers consumption of SAW atomization suggests that the SAW atomizer can be miniaturized into dimensions commensurate with portable consumer devices.

In this paper, we demonstrate the use of wireless acoustic communications through the human body, in-vivo. The acoustic communications signals are intended to be used for fixed in-vivo biomedical devices. In-vivo biomedical devices include, for example, pacemakers, but more importantly, neural implants. The use of acoustic communications for neural implants represents a significant improvement as wired and wireless RF communications cannot be utilised. The acoustic communications channel comprises of a piezoelectric transducer as the transmitter, a section of the human body as the transmission medium, and a second piezoelectric transducer as the receiver. In this initial work, a forearm was used as the transmission medium. Communicating acoustically through the human body was successfully achieved. We present results showing the performance of the acoustic communications channel. The frequency response, transfer function and transient response (at resonance) of the communications channel were measured. Due to the frequency response of the communications channel, phase shift keying was chosen as the digital modulation method. Sample communications signals are included. For comparison, amplitude shift keying results are also shown. The results suggest that a data rate of over 10kbps could be achieved with the configuration used.

A recently proposed mean-field theory of mammalian cortex rhythmogenesis describes the salient features of electrical activity in the cerebral macrocolumn, with the use of inhibitory and excitatory neuronal populations (Liley et al 2002). This model is capable of producing a range of important human EEG (electroencephalogram) features such as the alpha rhythm, the 40 Hz activity thought to be associated with conscious awareness (Bojak & Liley 2007) and the changes in EEG spectral power associated with general anesthetic effect (Bojak & Liley 2005). From the point of view of nonlinear dynamics, the model entails a vast parameter space within which multistability, pseudoperiodic regimes, various routes to chaos, fat fractals and rich bifurcation scenarios occur for physiologically relevant parameter values (van Veen & Liley 2006). The origin and the character of this complex behaviour, and its relevance for EEG activity will be illustrated. The existence of short-lived unstable brain states will also be discussed in terms of the available theoretical and experimental results. A perspective on future analysis will conclude the presentation.

Modelling of non-stationary cardiac structures is complicated by the complexity of their intrinsic and extrinsic motion. The first known study of haemodynamics due to the beating of heart was made by Leonardo Da Vinci, giving the idea of fluid-solid interaction by describing how vortices develop during cardiac structural interaction with the blood. Heart morphology affects in changes of cardio dynamics during the systolic and diastolic phrases. In a chamber of the heart, vortices are discovered to exist as the result of the unique morphological changes of the cardiac chamber wall by using flow-imaging techniques such as phase contrast magnetic resonance imaging. The first part of this paper attempts to quantify vortex characteristics by means of calculating vorticity numerically and devising two dimensional vortical flow maps. The technique relies on determining the properties of vorticity using a statistical quantification of the flow maps and comparison of these quantities based on different scenarios. As the characteristics of our vorticity maps vary depending on the phase of a cardiac cycle, there is a need for robust quantification method to analyse vorticity. In the second part of the paper, the approach is then utilised for examining vortices within the human right atrium. Our study has shown that a proper quantification of vorticity for the flow field can indicate the strength and number of vortices within a heart chamber.

Anesthetics such as isoflurane adversely affect heart rate. In this study we analysed the interaction between heart rhythm and respiration at different concentrations of isoflurane and ventilation rates. In two rats, the electrocardiogram (ECG) and respiratory signals were recorded under the influence of isoflurane. For the assessment of cardiorespiratory coordination, we analysed the phase locking between heart rate, computed from the R-R intervals of body surface ECG, and respiratory rate, computed from impedance changes, using Hilbert transform. The changes in heart rate, percentage of synchronization and duration of synchronized epochs at different isoflurane concentrations and ventilation rates were assessed using linear regression model. From this study it appears that the amount of phase locking between cardiac and respiratory rates increases with the increase in concentration of isoflurane. Heart rate and duration of synchronized epochs increased significantly with the increase in the level of isoflurane concentration while respiratory rate was not significantly affected. Cardiorespiratory coordination also showed a considerable increase at the ventilation rates of 50- 55 cpm in both the rats, suggesting that the phase-locking between the cardiac and respiratory oscillators can be increased by breathing at a particular respiratory frequency.

Many mining operations use large quantities of water to separate valuable minerals from less valuable gangue. This dependence on liquid separation has an environmental impact in terms of energy and water use and also implies a cap on production due to the availability of water. To address these problems, the CSIRO has developed the CSIRO Rotational Classifier, which - by using the phenomena of rotational segregation - can quickly separate dry granular material in terms of size and/or density without the use of any liquids. The purpose of this paper is to obtain a deeper understanding of how rotational segregation can separate particles of different densities in a rotating cylinder, free from any interstitial fluids. This was accomplished by analyzing a cross section at the 20% fill level in a 50% full classifier, which contained a 50-50 ratio of glass and lead beads. The granular bed was sampled at different time intervals over a 60 second period with a classifier rotation rate of 2 rpm. These experiments resulted in a high segregation level of 0.9 in 20 seconds and 0.95 by 60 seconds (where a level of 1 implies full segregation). The results then underwent image analysis and were subsequently compared to results from a discrete element method (DEM) model where similar segregation ratios, albeit at longer timescales, were obtained. This study gave a further insight into the segregation process particularly in terms of axial formation of the segregated core which may one day be used in the separation of minerals.

The aim of this paper is to simulate profit expectations as an emergent property using an agent based model. The paper builds upon adaptive expectations, interactive expectations and small world networks, combining them into a single adaptive interactive profit expectations model (AIE). Understanding the diffusion of interactive expectations is aided by using a network to simulate the flow of information between firms. The AIE model is tested against a profit expectations survey. The paper introduces "runtime weighted model averaging" and the "pressure to change profit expectations index" (p^x). Runtime weighted model averaging combines the Bayesian Information Criteria and Kolmogorov's Complexity to enhance the prediction performance of models with varying complexity but a fixed number of parameters. The p^x is a subjective measure representing decision making in the face of uncertainty. The paper benchmarks the AIE model against the rational expectations hypothesis, finding the firms may have adequate memory although the interactive component of AIE model needs improvement. Additionally the paper investigates the efficacy of a tuneable network and equilibrium averaging. The tuneable network produces widely spaced multiple equilibria and runtime weighted model averaging improves prediction but there are issues with calibration.

Capillary Electrophoresis (CE) is a separation technique that can be used as a sample pre-treatment step in chemical analysis. When coupled with a detection technique, identification of chemical species can be performed on the basis of the elution signals. However, the sensor signals are often complicated by high signal noise, varying baseline and overlapping peaks. There is thus a need for a signal processing technique capable of robustly detecting peaks in acquired sensor data. Here, we report on an algorithm that utilises the Continuous Wavelet Transform (CWT) for the detection of analyte peaks. The algorithm that has been developed makes use of a wavelet equal to the first derivative of a Gaussian function and has been successfully applied to data obtained from a CCD sensor fabricated on a polymer microfluidic separation chip. The algorithm operates by taking the CWT of the sensor response. It then analyses patterns in the local maximum and minimum points evident across scales in the CWT coefficients to find the peaks in the time series data. The performance of two versions of the algorithm have been compared for synthetic data sets each with known baseline, peaks and noise. The improved algorithm has been shown to successfully find peaks with a high sensitivity and low False Discovery Rate within a range of sensitivities.

Scalar transport in closed potential flows is investigated for the specific case of a periodically reoriented dipole flow. For scalar advection, Lagrangian chaos can be achieved with breakdown of the regular Hamiltonian structure, which is governed by symmetry conditions imposed by the dipole flow. Instability envelopes associated with period-doubling bifurcations of fixed points govern which regions of the flow control parameter space admits global chaos. These are further refined via calculation of Lyapunov exponents. These results suggest significant scalar transport enhancement is possible within potential flows, given appropriate programming of stirring protocols.

We study aperiodic stochastic resonant data storage in an extended system evolving on directed small-world networks. Each node of the network represents a dynamical bistable system, and nodes are randomly connected by the directed shortcuts with a rewiring probability. The constructive role of the internal noise and the random connectivity is characterized by the bit error rate and demonstrated in numerical simulations. Random internal noise in each node enhances the survival of a short-time length of binary signal via aperiodic stochastic resonance. Interestingly, random connectivity further improves the propagation time of binary information through the small-world architecture.

Metastasis of cancer requires adhesion and migration of cells. The effect of chemokine gradient on prostate cancer cells (PCC) is not well understood. A poly-dimethylsiloxane (PDMS) microfluidic device that enables time-lapse study of cell migration is presented. Photolithography and soft lithography processes were used to fabricate the PDMS devices from SU-8 molds. The device has two inlets, a cell reservoir and an outlet channel with a depth of 100μm. The microfluidic device is configured to provide fluid mixing leading to a gradient across the outlet channel. The inlets allow for introduction of different chemokines at different concentrations and flow rates. The cell migration in the presence of chemokine gradient and flow rate can thus be monitored in a time-lapse fashion. The gradient formations at different flow rates over different lengths of time have been analyzed. Flow rates of 2, 3, 6, 8, 10, 20 μl/min at 5-minute intervals for over an hour were monitored to determine optimum flow rates and times required to produce desired gradient profiles. Results suggest that gradients formed at lower flow rates have less variation over time. Moreover, lower flow rates do not affect cell movement making observation of cell migration towards gradients possible. Higher flow rates have better gradient definition but cells tend to flow away with the fluid.

In conventional time-domain Optical Coherence Tomography (OCT), a moving mirror is used as a reference optical delay line. This motion can result in instrument degradation, and in some situations it is preferable to have no moving parts. Stationary optical delay lines using a variety of methods have been proposed. Of particular interest, due to its low cost, is the use of a micro-photonic stationary optical delay line, made up of an addressable Stepped Mirror Structure (SMS) using a liquid crystal optical switch. Here the individual steps of the SMS can be selected by the liquid crystal array. For use in OCT, the discrete nature of the SMS needs to be overcome by having the step height less than the coherence length of the low coherent light source. Typical coherence lengths in current OCT systems are on the order of 10μm. Hence, micrometer size steps require the use of a relevant fabrication method. In this paper, we compare SMSs fabricated using wet and dry etching methods. Specifically, Reactive Ion Etching (RIE) using CF₄/O₂ and chemical bath etching, using a solution of HF, HNO₃ and Acetic acid. Three inch diameter silicon wafers, 400μm thick, were etched by both methods. The RIE was used to produce a SMS with five 5μm high steps each step approximately 1 cm wide. The wet etching produced an SMS with three 15μm steps approximately 2 cm wide. The overall structures of the SMSs were compared using optical profilometry. The RIE step quality was far superior to the wet etch method due to the ability to control the anisotropy of the RIE method.

SBA-15 and SBA-16 nanostucrured materials were synthesized via hydrothermal treatment and were functionalized with 3-aminopropyltriethoxysilane (APTES), and vinyltriethoxysilane (VTES). The obtained samples were characterized by different techniques such as XRD, BET, IR and TEM. After functionalization, it showed that these nanostrucrured materials were still maintained the hexagonal pore structure of the parent SBA-15 and cubic cage structure of the parent SBA-16. The non-functionalized pure silica SBA-15 and SBA-16 as well as functionalized SBA-15 and SBA-16 materials were used to immobilize DAAO, which is industrially important enzyme for the production of glutaryl 7-amino cephalosporanic acid (GL-7-ACA) from cephalosporin C (CPC). The obtained results revealed that functionalized SBA- 15 and SBA-16 materials exhibited higher enzymatic activity and stability than those of non-functionalized ones. This might be due to the enhancing of surface hydrophobicity upon functionalization. The surface functionalization of the nanostructured silicas with organic groups can enhance the interaction between enzyme and the supports and consequently increasing the operational stability of the immobilized enzyme. The loading of enzyme on SBA-15 materials was higher than that on SBA-16 samples (both functionalized and non-functionalized types). This might be explained by the difference in pore size and type (cylindrical for SBA-15 and bottle-neck for SBA-16) as well as structure shape (hexagonal for SBA-15 and cubic cage for SBA-16) of both mesoporous materials. Additionally, nature of functionalized groups significantly affected the enzymatic activity. Effects on surface binding force, nature of functional groups, pore size of supports were investigated and discussed.

Inductively coupled RF telemetry is an optimal method for both power supply and data transmission in long term artificial implants due to small size, high reliability, and extended life span of the device. In this research, we propose the use of the same technique for secure remote interrogation and powering of a human implantable, Surface Acoustic Wave (SAW) correlation based, passive microvalve. This is carried out by interrogating the microvalve with a Barker sequence encoded BPSK signal. In this paper we present the development of a FEM model for the derivation of the induced voltage on a miniature (2.5×2.5×1 mm), inductively coupled, biocompatible spiral antenna/coil, interrogated by a 7.5×7.5×0.2 cm spiral antenna/coil in the near field. The amount of power transferred at a 30-160 MHz range was derived using the S₂₁ coupling response when the two antennas are separated by a human body simulant of 5 cm depth. Furthermore, the effect of varying magnetic coupling on the induced voltage, due to the misorientation of coils/antennas is analysed.

Semiconductor quantum dots (QDs) are tiny light-emitting particles on the nanometer scale, and are emerging as a new class of fluorescent labels for biology and medicine. In comparison with organic dyes and fluorescent proteins, they have unique optical and electronic properties, with size-tunable light emission, superior signal brightness, resistance to photobleaching, and broad absorption spectra for simultaneous excitation of multiple fluorescence colors. We described the preparation and characterization of various surface coated luminescent semiconductor CdTe/CdS QDs for biological labeling. This study demonstrates the cytotoxicity and cellular uptake of all six surface-modified QDs. QD-surface modifications do play a significant role in cell cytotoxicity. In addition, increasing cytotoxicity with higher QD concentration for various surface coated QDs was observed. By demonstrating how nanoparticle surface coatings can influence cell toxicity, these results serve to suggest an additional factor to be considered in the design of biocompatible nanomaterials for future biological applications.

This work describes the innovative development of high throughput human DNA purification process using the molecular self-assembled mesoporous silica nanoparticles. The mesoporous silica nanoparticles were prepared by sol-gel method and the formation of molecular self-assembled monolayers with functional groups was chemically demonstrated. The surface modification of functional groups was performed with aminofunctionallized organic silanes on mesoporous silica nanoparticles and the results of DNA separation was represented with electrophoresis images.

Work presented here describes a simple and convenient process to highly efficient and direct DNA separation with functionalized silica-coated magnetic nanoparticles. Iron oxide magnetic nanoparticles and silica-coated magnetic nanoparticles were obtained uniformly and the silica coating thickness could be easily controlled in a range from 10 to 50 nm by changing the concentration of silica precursor (TEOS) including the controlled magnetic strength and particle size. A change in the surface hydrophilicity on the nanoparticles was introduced by aminosilanization to enhance the selective DNA separation resulting from electrostatic interaction. The efficiency of the DNA separation was explored via the function of the amino-group numbers, particle size, the amount of the nanoparticles used, and the concentration of NaCl salt.