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Transfection of difficult-to-transfect rat primary cortical neurons with magnetic nanoparticles
No full textThe efficient cell transfection method is vital for various biomedical applications, such as the CRISPR-Cas9 technique. Current cell transfection methods, including lipofectamine, calcium phosphate co-precipitation, nucleofection, and viral infection are not equally efficient for various cells and have their disadvantages. In this study, a magnetic nanoparticle (MNP)-based method was introduced for delivering both FITC dye and a functional EGFP gene into easy-to-transfect HEK cells and difficult-to-transfect rat primary cortical neurons. The transfection efficacy could be controlled in both time-dependent and magnetic strength-dependent manner. This cell transfection method could have substantial potential for targeted drug delivery.Peer reviewed: YesNRC publication: Ye
Wavefront control architecture and expected performance for the TMT Planetary Systems Imager
No full textThe Planetary Systems Imager (PSI) is a modular instrument optimized for direct imaging and characterization of exoplanet and disks with the Thirty Meter Telescope (TMT). PSI will operate across a wide wavelength range ( 480.6 - 5\u3bcm) to image exoplanets and circumstellar disks in both reflected light and thermal emission. Thanks to the TMT\u2019s large collecting area, PSI will have the sensitivity to directly image and spectrally characterize large gaseous planets with unprecedented sensitivity. PSI will also be capable of imaging rocky planets in the habitable zones of the nearest M-type stars in reflected light and search for biomarkers in their atmospheres. Imaging habitable planets in reflected light is PSI\u2019s most challenging goal, requiring high contrast imaging (HCI) capabilities well beyond what current instruments achieve. This science goal drives PSI\u2019s wavefront sensing and control requirements and defines the corresponding architecture discussed in this paper. We show that PSI must deliver 1e-5 image contrast 4815 mas separation at \u3bb 48 1\u3bcm-1.5\u3bcm, and that a conventional extreme-AO architecture relying on a single high speed wavefront sensor (WFS) is not sufficient to meet this requirement. We propose a wavefront control architecture relying on both visible light (\u3bb < 1.1 \u3bcm) sensing to optimize sensitivity, and near-IR (\u3bb > 1.1 \u3bcm) sensors to address wavefront chromaticity terms and provide high contrast imaging capability. We show that this combination will enable speckle halo suppression at the < 1e-5 raw contrast level in near-IR, allowing detection and spectroscopic characterization of potentially habitable exoplanets orbiting nearby M-type stars.Peer reviewed: YesNRC publication: Ye
Aerodynamic characteristics of generic ice shells
No full textFreezing rain and wet snow can cause ice to accumulate on the surface of bridge cables. Subsequently, a rise in temperature and wind can cause ice to shed from the surface of cables. Several instances of ice and wet snow shedding from bridge cables have been observed in Canada. Environmental predictive models have been proposed to predict the ice shedding behaviour and its trajectory from bridge cables. The current study aims at measuring the aerodynamic force and moment coefficients of generic ice fragments detached from a bridge cable as a priori for a subsequent ice trajectory model. Nine representative generic, ice shells were selected to represent different aspect ratios, curvatures, ice thicknesses, and external ice surface conditions. Aerodynamic forces and moments were measured for each of the ice shell models in turbulent flow for a wide range of orientations. The use of a curved shape as opposed to a flat plate resulted in a significant difference in the aerodynamic coefficients. It was found that the aspect ratio was the most important geometric factor in determining the aerodynamic forces and moments on the curved models. The findings of this study will be implemented in future ice trajectory models.Peer reviewed: YesNRC publication: Ye
Experimental study of the impacts of porous plates on steady flow velocities for hydrokinetic energy resource impact assessment applications
No full textIn order to take advantage of economies of scale, hydrokinetic energy (HKE) developers typically deploy multiple turbines within rivers or the marine environment in array or farm configurations. Successful planning and design of turbine array deployments requires an understanding of turbine wake hydrodynamics, wake interactions within arrays, and the performance of turbines within array fields, to enable quantification of the extractable power and impacts on the surrounding environment. However, consistent and reliable methods for predicting the power generation capabilities of turbine arrays and the total extractable power from a given site remain elusive. Numerical hydrodynamic models show considerable promise as tools to support hydrokinetic energy resource assessment, turbine array site selection, array design and impact assessment. For example, Computational Fluid Dynamics (CFD) models provide a means to analyse the high frequency motions and complex geometries associated with turbine-fluid interactions at the scale of individual turbines. CFD models can be integrated with numerical models that solve free surface flow equations to study the interactions between turbine arrays and hydrodynamics at coastal region or river reach scales. However, numerical models remain subject to limitations and require calibration and validation to provide confidence in their predictive capabilities, and to quantify uncertainty. This paper presents preliminary work whereby a set of large scale physical models was utilized to document the magnitude and spatial distribution of the velocity deficit at a high resolution upstream, and within the downstream wake, of simplified representations of cross-flow turbines modelled as porous rectangular plates. Subsequent phases of the research will include using this experimental data to calibrate and validate a CFD model of the porous plates, and conducting scale model experiments using more realistic, moving cross-flow hydrokinetic turbines to support improvements in CFD modelling techniques for HKE applications.Peer reviewed: YesNRC publication: Ye
Physical model testing for supporting ice force model development of DP vessels in managed ice
No full textThe stationkeeping performance prediction of a Dynamic Positioning (DP) vessel greatly depends on the accurate modelling of the ice forces, which in turn depends on managed ice field characteristics (ice concentration, floe thickness, floe size, ice drift speed and direction and inclusion of brash ice and small ice pieces) and the DP system characteristics (DP gain set-ups, control algorithms etc.). Physical model testing is a key tool in understanding and validating the fundamental relationships between the ice environmental parameters and the dynamics of a DP vessel. The National Research Council's Ocean Coastal and River Engineering Research Centre (NRC-OCRE) has conducted two comprehensive series of experiments with one 1/40 scaled and one 1/19 scaled DP vessels, in various realistic managed ice conditions in the ice tank facility in early 2015 and in early 2018, respectively. The primary objective of the model testing programs was to generate a database on managed ice-DP vessel interactions, which was the core to NRC-OCRE's ice force model development and validation activities.
This paper describes the model test planning, preparation of managed ice field, the procedure of the model tests and the methodologies of data analysis for the two model testing programs. In both programs, the physical and mechanical characteristics of the ice field were modelled by controlling ice concentration, ice thickness, floe size, ice strength and the ice drift speed and direction. The ice concentration ranged from a light condition (7/10th) to a very heavy condition (9/10th+) with multiple ice floe sizes ranging between 12.5m to 100m. Multiple ice thicknesses ranging between 0.4m to 2m were used for multiple ice drift speeds (0.2 knots, 0.5 knots, and 1.2 knots) with various moderate to extreme ice encroachment angles. Ice forces were not measured directly but estimated based on the thrusters\u2019 response. In addition, model's 6-DOF motions and accelerations were recorded. Multiple high definition cameras were used to capture the global and local ice-structure interactions both placed in above water and underwater locations. For the 2018 testing program, a new ceiling based video system was introduced that captured the images of the ice basin at multiple overlapping locations, which were processed offline to obtain time sequence full image of the ice basin.
Model testing results for a few representative cases are presented in this article. The DP system used in the testing demonstrated capabilities of the vessel in maintaining station for majority of test cases. The measurements as well as the videos showed complex and highly stochastic ice-ship-boundary wall interactions, particularly for high oblique cases. The data and video captured provided sufficient information for developing novel ice force models for real time applications.Peer reviewed: NoNRC publication: Ye
Emerging technologies and learning innovation in the new learning ecosystem
No full textThis paper highlights a decade of research by the National Research Council in the area of Personal Learning Environments, including MOOCs and learning in networked environments. The value of data analytics, algorithms, and machine learning is explored in more depth, as well as challenges in using personal learning data to automate the learning process, the use of personal learning data in educational data mining (EDM), and important ethics and privacy issues around networked learning environments.Peer reviewed: YesNRC publication: Ye
Estimate of scattering truncation in the cavity attenuated phase shift PMSSA monitor using the radiative transfer theory
No full textThe recently developed cavity attenuated phase shift particulate matter single scattering albedo (CAPS PMssA) monitor has been shown to be fairly accurate and robust for real-time aerosol optical properties measurements. The scattering component of the measurement undergoes a truncation error due to the loss of scattered light from the sample tube in both the forward and backward directions. Previous studies estimated the loss of scattered light typically using the Mie theory for spherical particles, assuming particles are present only on the sampling tube centerline, and without accounting for the effects of sampling tube surface reflection. This study overcomes these limitations by solving the radiative transfer equation in an axisymmetric absorbing and scattering medium using the discrete\uad ordinates method to estimate the scattering truncation error. The present mode! predicted larger scattering loss than the simplified theoretical estimate in the literature. The effects of absorption coefficient, scattering coefficient, asymmetry parameter of the scattering phase function, and the reflection coefficient at the sampling tube inner surface were investigated . Under typical conditions of CAPS PMssA operation of low extinction coefficients below about 5000 Mm- 1 the scattering loss remains independent of the absorption and scattering coefficients but is dependent on the asymmetry parameter of the scattering phase function and the reflection coefficient of the sampling glass tube inner surface. The scattering loss increases with increasing bath the asymmetry parameter and the surface reflection coefficient.Peer reviewed: YesNRC publication: Ye
Real-time monitoring of a microbial electrolysis cell using an electrical equivalent circuit model
No full textEfforts in developing microbial electrolysis cells (MECs) resulted in several novel approaches for wastewater treatment and bioelectrosynthesis. Practical implementation of these approaches necessitates the development of an adequate system for real-time (on-line) monitoring and diagnostics of MEC performance. This study describes a simple MEC equivalent electrical circuit (EEC) model and a parameter estimation procedure, which enable such real-time monitoring. The proposed approach involves MEC voltage and current measurements during its operation with periodic power supply connection/disconnection (on/off operation) followed by parameter estimation using either numerical or analytical solution of the model. The proposed monitoring approach is demonstrated using a membraneless MEC with flow-through porous electrodes. Laboratory tests showed that changes in the influent carbon source concentration and composition significantly affect MEC total internal resistance and capacitance estimated by the model. Fast response of these EEC model parameters to changes in operating conditions enables the development of a model-based approach for real-time monitoring and fault detection.Peer reviewed: YesNRC publication: Ye
Traumatic brain injury: classification, models and markers
No full textTraumatic brain injury (TBI) is a leading cause of morbidity and mortality worldwide. Due to its high incidence rate and often long-term sequelae, TBI contributes significantly to increasing costs of medicare expenditures annually. Unfortunately, advances in the field have been stifled by patient and injury heterogeneity that pose a major challenge in TBI prevention, diagnosis and treatment. In this review, we briefly discuss the causes of TBI, followed by its prevalence, classification and pathophysiology. The current imaging detection methods and animal models used to study brain injury are examined. We discuss the potential use of molecular markers in detecting and monitoring the progression of TBI, with particular emphasis on microRNAs as a novel class of molecular modulators of injury and its repair in the neural tissue.Peer reviewed: YesNRC publication: Ye