Real-time, step-wise, electrical detection of protein molecules using dielectrophoretically aligned SWNT-film FET aptasensors

Aptamer functionalized addressable SWNT-film arrays between cantilever electrodes were successfully developed for biosensor applications. Dielectrophoretically aligned SWNT suspended films made possible highly specific and rapid detection of target proteins with a large binding surface area. Thrombin aptamer immobilized SWNT-film FET biosensor resulted in a real-time, label-free, and electrical detection of thrombin molecules down to a concentration of ca. 7 pM with a step-wise rapid response time of several seconds.X113338sciescopu

Suspended sand concentration models under breaking waves: Evaluation of new and existing formulations

A total of 7 reference concentration (C₀) models (6 existing and 1 newly proposed) were validated against 119 test cases from 4 recently published datasets collected under the LIP, CROSSTEX, SandT-Pro and SINBAD experimental studies. These models were evaluated for performance in different cross-shore regions: the shoaling zone, breaking (outer surf) zone and inner surf zone, under regular and irregular breaking wave conditions. In almost all existing C₀ models, substantial under-prediction was found particularly around the wave plunging point (point at which breaking wave plunges and surface generated turbulent kinetic energy, TKE, is injected into the water column) where strong localised increases in C₀ were observed. This strong increase in concentration was attributed to the large-scale breaking-generated turbulent vortices invading the wave bottom boundary layer (WBBL) and entraining dense clouds of sediment near the plunging point. Models that were directly or indirectly driven by local wave climate such as the local wave height (H), breaker height (Hb) or local water depth (d), were found to perform quite poorly in the breaking region under regular and irregular plunging breaker waves. Formulations that related C₀ to the sand pickup rate (i.e. depending on exerted bed shear exceeding critical bed shear for entrainment) were adept in regions unaffected by external breaking-induced TKE (e.g. the shoaling zone) but could not account for the high levels of concentration observed at the plunging point. This is because these formulations were based on the implicit assumption that sediment entrainment is only induced by the local TKE generated by bed shear; not taking surface-generated breaking-induced TKE into account. This assumption was addressed in more recent studies, by including breaking-induced TKE into sediment pickup rate or reference concentration formulations. Though latest studies have shown promising relationships between near-bed TKE (kb) and reference concentration/sediment pickup, such formulations also face inherent limitations. These formulations are highly dependent on the accuracy of measured or modelled kb and are also sensitive to the magnitude of k. For example, the magnitude of measured kb was found to vary by a factor of 1.1–1.3 between regular and irregular wave conditions, with kb being smaller under irregular wave conditions. This resulted in varied performance between datasets in kb-driven reference concentration formulations. The Froude-scaled TKE produced smaller deviations in magnitude of TKE between datasets, suggesting that it may be a more suitable driving parameter for reference concentration models than kb. A new reference concentration model, L19, was empirically derived from an inverse relationship observed between d and C₀, and from the roller energy dissipation rate. The newly proposed L19 model shows good agreement with measured C₀ (with RMSE ranging between 0.36 and 1.79 kg/m³ over the different datasets) in regular and irregular wave conditions, even at the plunging point where concentration is highest. The modified concentration profile [C(z)] equation also performs well, generally capturing the vertical concentration profile accurately throughout the whole water column

Corrigendum to “Suspended sand concentration models under breaking waves: Evaluation of new and existing formulations” [Marine Geology 426 (2020) 106197]

Refers to: Lim, G., Jayaratne, R. and Shibayama, T. 2020. Suspended sand concentration models under breaking waves: Evaluation of new and existing formulations. Marine Geology. 246 (Art. 106197). https://doi.org/10.1016/j.margeo.2020.10619

New Suspended Sand Concentration Model for Breaking Waves

Process-based morphodynamic modelling suites (as well as other process-based models) are often considered to be inefficient and unsuitable for simulating medium- to long-term morphodynamics due to the various theoretical (e.g. robustness of sediment transport models) and practical (e.g. computational costs) limitations. In particular, a lack of knowledge of sediment transport processes and how they relate to hydrodynamics makes the application of short-term models to long-term coastal evolution challenging. Even the state-of-the-art coastal area modelling suites (such as Delft3D and MIKE21) consist of relatively simple physics, relying instead on numerous semi-empirical parameterizations, which are often poorly supported by measured data and/or physical process understanding. In particular, suspended sediment transport in the highly turbulent surf zone is poorly modelled under breaking wave conditions. Six existing suspended sand concentration (SSC) models were critically evaluated against four high-resolution datasets with field-scale breaking waves and co-located velocity and concentration measurements over multiple cross-shore zones (shoaling, breaking and inner-surf zones). A new improved concentration model was proposed based on a novel empirical relationship observed between local water depth and reference concentration, as well as latest process understanding and insights

Image interpolation using Shearlet based iterative refinement

This paper proposes an image interpolation algorithm exploiting sparse representation for natural images. It involves three main steps: (a) obtaining an initial estimate of the high resolution image using linear methods like FIR filtering, (b) promoting sparsity in a selected dictionary through iterative thresholding, and (c) extracting high frequency information from the approximation to refine the initial estimate. For the sparse modeling, a shearlet dictionary is chosen to yield a multiscale directional representation. The proposed algorithm is compared to several state-of-the-art methods to assess its objective as well as subjective performance. Compared to the cubic spline interpolation method, an average PSNR gain of around 0.8 dB is observed over a dataset of 200 images

Reversibility of Red blood Cell deformation

The ability of cells to undergo reversible shape changes is often crucial to their survival. For Red Blood Cells (RBCs), irreversible alteration of the cell shape and flexibility often causes anemia. Here we show theoretically that RBCs may react irreversibly to mechanical perturbations because of tensile stress in their cytoskeleton. The transient polymerization of protein fibers inside the cell seen in sickle cell anemia or a transient external force can trigger the formation of a cytoskeleton-free membrane protrusion of micrometer dimensions. The complex relaxation kinetics of the cell shape is shown to be responsible for selecting the final state once the perturbation is removed, thereby controlling the reversibility of the deformation. In some case, tubular protrusion are expected to relax via a peculiar "pearling instability".Comment: 4 pages, 3 figure

Rotating Electromagnetic Waves in Toroid-Shaped Regions

Electromagnetic waves, solving the full set of Maxwell equations in vacuum, are numerically computed. These waves occupy a fixed bounded region of the three dimensional space, topologically equivalent to a toroid. Thus, their fluid dynamics analogs are vortex rings. An analysis of the shape of the sections of the rings, depending on the angular speed of rotation and the major diameter, is carried out. Successively, spherical electromagnetic vortex rings of Hill's type are taken into consideration. For some interesting peculiar configurations, explicit numerical solutions are exhibited.Comment: 27 pages, 40 figure

Measurement and control systems for an imaging electromagnetic flow meter

Electromagnetic flow metres based on the principles of Faraday's laws of induction have been used successfully in many industries. The conventional electromagnetic flow metre can measure the mean liquid velocity in axisymmetric single phase flows. However, in order to achieve velocity profile measurements in single phase flows with non-uniform velocity profiles, a novel imaging electromagnetic flow metre (IEF) has been developed which is described in this paper. The novel electromagnetic flow metre which is based on the ‘weight value’ theory to reconstruct velocity profiles is interfaced with a ‘Microrobotics VM1’ microcontroller as a stand-alone unit. The work undertaken in the paper demonstrates that an imaging electromagnetic flow metre for liquid velocity profile measurement is an instrument that is highly suited for control via a microcontroller