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Large magnetoresistance by Pauli blockade in hydrogenated graphene
No full textWe report the observation of a giant positive magnetoresistance in millimeter-scale hydrogenated graphene with the magnetic field oriented in the plane of the graphene sheet. A positive magnetoresistance in excess of 200% at a temperature of 300 mK was observed in this configuration, reverting to negative magnetoresistance with the magnetic field oriented normal to the graphene plane. We attribute the observed positive in-plane magnetoresistance to a Pauli blockade of hopping conduction induced by spin polarization. Our Rapid Communication shows that spin polarization in concert with electron-electron interaction can play a dominant role in magnetotransport within an atomic monolayer.Peer reviewed: YesNRC publication: Ye
Lipofection of plasmid DNA into human mast cell lines using lipid nanoparticles generated by microfluidic mixing
No full textMast cells are important immune cells that have significant roles in mediating allergy and asthma. Therefore, studying the molecular mechanisms regulating these and other processes in mast cells is important to elucidate. Methods such as lipofection, transduction, and electroporation are often employed to dissect these mechanisms by disrupting gene expression in mast cell lines. However, as with other leukocytes, human mast cells (HMCs) are often refractory to the delivery of plasmids by lipofection. In this study, we investigated the utility of lipid nanoparticles (LNPs) containing the ionizable cationic lipids 1,2\u2010dioleoyloxy\u20103\u2010dimethylaminopropane, 1,2\u2010dioleyloxy\u20103\u2010dimethylaminopropane, or 2,2\u2010dilinoleyl\u20104\u2010(2\u2010dimethylaminoethyl)\u2010[1,3]\u2010dioxolane for the delivery of plasmid DNA into HMC lines. Herein, we demonstrate for the first time the use of LNPs to achieve significant and reproducible levels of plasmid DNA transfection in HMC\u20101.2 and laboratory of allergic diseases 2 (LAD2) cells. These levels reached 53.2% and 16.0% in HMC\u20101.2 and LAD2 cells, respectively; and outperformed Lipofectamine 3000 in both cases. Moreover, cell viability in the transfected cells remained above 65% for all LNP conditions tested. Together, these observations illustrate the efficacy of this technique for mast cell researchers and further support the use of LNPs for nucleic acid delivery into leukocytes.Peer reviewed: YesNRC publication: Ye
Dynamic model of a municipal wastewater stabilization pond in the arctic
No full textWaste stabilisation ponds (WSPs) are the method of choice for sewage treatment in most arctic communities because they can operate in extreme climate conditions, require a relatively modest investment, are passive and therefore easy and inexpensive to operate and maintain. However, most arctic WSPs are currently limited in their ability to remove carbonaceous biochemical oxygen demand (CBOD), total suspended solids (TSS) and ammonia-nitrogen. An arctic WSP differs from a \u2018southern\u2019 WSP in the way it is operated and in the conditions under which it operates. Consequently, existing WSP models cannot be used to gain better understanding of the arctic lagoon performance. This work describes an Arctic-specific WSP model. It accounts for both aerobic and anaerobic degradation pathways of organic materials and considers the periodic nature of WSP operation as well as the partial or complete freeze of the water in the WSP during winter. A uniform, multi-layer (ice, aerobic, anaerobic and sludge) approach was taken in the model development, which simplified and expedited numerical solution of the model, enabling efficient model calibration to available field data.Peer reviewed: YesNRC publication: Ye
Automated testing of optical fibres: towards the design of the Maunakea Spectroscopic Explorer Fibre Transmission System
No full textWe present the results of an automated fibre optic test bench constructed at the University of Victoria as part of the Maunakea Spectroscopic Explorer (MSE) Fibre Transmission System (FiTS). In preparation for MSE-FiTS, we have begun characterizing the focal ratio degradation (FRD) of candidate multi-mode fibres with the ultimate goal of testing all 4000 MSE fibres. To achieve this, we have built an optical bench to perform an automated version of the collimated beam test. Herein we present the design of the bench and discuss the automation of components by introducing the Big FiTS Fibre Wrapper (Big FFW), our open-source automation software. We conclude with the results of tests performed using the Big FFW on a sample of candidate fibre, comparing the Big FFW results against those found using manual methods. Our results suggest that the candidate MSE fibre meets the science requirement of < 5% FRD at f /2 and find less than 1% disagreement between both measurement methods.Peer reviewed: YesNRC publication: Ye
Contribution of model predictive control in the integration of renewable energy sources within the built environment
No full textIntegrating intermittent renewable energy sources has renders the power network operator task of balancing electricity generation and consumption increasingly challenging. Aside from heavily investing in additional storage capacities, an interesting solution might be the use predictive control methods to shift controllable loads toward production periods. Therefore, this article introduces a systematic approach to provide a preliminary evaluation of the thermoeconomic impact of model predictive control (MPC) when being applied to modern and complex building energy systems (BES). The proposed method applies an \u3f5-constraint multi-objective optimization to generate a large panel of different BES configurations and their respective operating strategies. The problem formulation relies on a holistic BES framework to satisfy the different building service requirements using a mixed-integer linear programming technique. To illustrate the contribution of MPC, different applications on the single- and multi-dwelling level are presented and analyzed. The results suggest that MPC can facilitate the integration of renewable energy sources within the built environment by adjusting the heating and cooling demand to the fluctuating renewable generation, increasing the share of self-consumption by up to 27% while decreasing the operating expenses by up to 3% on the single-building level. Finally, a preliminary assessment of the national-wide potential is performed by means of an extended implementation on the Swiss building stock.Peer reviewed: YesNRC publication: Ye
Current state and future prospects for liquid biofuels in Canada
No full textThe necessity to find renewable and low carbon fuels as a critical component of the strategy to reduce greenhouse gas emissions in Canada has caused the biofuels industry to rapidly expand. However, there is a higher capacity for the use of biofuels to replace conventional petroleum fuels in Canada than outlined by cur rent regulations and programs. A wide range of feedstocks, processes, and applications for liquid biofuels can be found in Canada at varying degrees of progress. To reach the full potential of the biofuels industry in Canada, it is important to understand the broad landscape of the biofuels industry and areas of promise. The objective of this paper is to provide a comprehensive overview of the current state of liquid biofuels in Canada. This includes national feedstock availability and conversion processes to produce liquid biofuels. Both biochemical and thermochemical processes over a wide range of technology readiness levels, from R&D to commercialization, will be included. Current industry, government, and/or academic support for these production activities will b e referenced where applicable. The transportation applications of commercially available liquid biofuels in Canada will be reviewed. Finally, comments on future prospects to boost environmental and economic competitiveness of the biofuels industry in Canada will be provided.Peer reviewed: YesNRC publication: Ye
Demonstration of analyzers for multimode photonic time-bin qubits
No full textWe demonstrate two approaches for unbalanced interferometers as time-bin qubit analyzers for quantum communication, robust against mode distortions and polarization effects as expected from free-space quantum communication systems including wavefront deformations, path fluctuations, pointing errors, and optical elements. Despite strong spatial and temporal distortions of the optical mode of a time-bin qubit, entangled with a separate polarization qubit, we verify entanglement using the Negative Partial Transpose, with the measured visibility of up to 0.85\ub10.01. The robustness of the analyzers is further demonstrated for various angles of incidence up to 0.2 18. The output of the interferometers is coupled into multimode fiber yielding a high system throughput of 0.74. Therefore, these analyzers are suitable and efficient for quantum communication over multimode optical channels.Peer reviewed: YesNRC publication: Ye
Detection of azaspiracids in mussels using electrochemical immunosensors for fast screening in monitoring programs
No full textGiven the widespread occurrence of azaspiracids (AZAs), it is clearly necessary to advance in simple and low-cost methods for the rapid detection of these marine toxins in order to protect seafood consumers. To address this need, electrochemical immunosensors for the detection of AZAs based on a competitive direct immunoassay using peroxidase-labelled AZA as a tracer were developed. An anti-AZA polyclonal antibody was immobilised in a controlled and stable manner on protein G or avidin-coated electrodes. Experimental conditions were first optimised using colorimetric immunoassays on microtitre plates, providing intermediate products already applicable to the accurate detection of AZAs. Then, transfer of the protein G and avidin\u2013biotin interaction-based immunoassays to 8-electrode arrays provided compact and miniaturised devices for the high-throughput detection of AZAs. The low amounts of immunoreagents required as well as the potential for reusability of the avidin\u2013biotin interaction-based immunosensors represented significant economic savings as well as a contribution to sustainability. The electrochemical immunosensors enabled the quantification of all regulated AZAs below the regulatory limit, as well as a broad range of other toxic AZA analogues (from 63\u202f\ub1\u202f3 to 2841\u202f\ub1\u202f247\u202f\u3bcg AZA-1 equiv./kg for the protein G-based immunosensor and from 46\u202f\ub1\u202f2 to 3079\u202f\ub1\u202f358\u202f\u3bcg AZA-1 equiv./kg for the avidin\u2013biotin interaction-based immunosensor). The good agreement between the results obtained by the immunosensors and LC\u2013MS/MS in the analysis of naturally contaminated mussel samples demonstrated the easy implementation of electrochemical immunosensors for routine analysis of AZAs in food safety monitoring programs.Peer reviewed: YesNRC publication: Ye
Discrimination of uranium ore concentrates by chemometric data analysis to support provenance assessment for nuclear forensics applications
No full textThis work describes a method for the discrimination of uranium ore concentrates (UOCs) to support provenance assessment for nuclear forensics applications using samples representing twenty producers from around the world. The concentrations were measured using inductively coupled plasma mass spectrometry. UOCs were classified using the support vector machine method relying on 61 down to only 18 element concentrations without affecting the accuracy. New features are calculated from combination of elements from the selected 18 elements, and added to the selected elements improve the classification results. Reducing the number leads to the optimization of laboratory measurements of element signatures in support of nuclear safeguards and forensics applications.Peer reviewed: YesNRC publication: Ye
Dopant-modulated conjugated polymer enrichment of semiconducting SWCNTs
No full textConjugated polymer extraction (CPE) is a low-cost, scalable process that can enrich single-walled carbon nanotube (SWCNT) materials in organic media. For other separation methods in aqueous phases, redox chemistry and/or pH control dramatically affect the sorting process of the SWCNTs. We have previously determined that the CPE process can be fine-tuned by adjusting the pH on the tube surface. Here, we systematically studied the effect of redox chemistry on the CPE process by adding organic p-/n-dopants. At a very strong p-/n-doping level, static repulsions dominated the interactions between the tubes and the CPE lost selectivity. When the doping level changed from a medium p-doping to a neutral state, the yield of CPE increased and the selectivity was compromised. We also observed chiral selectivity when a weak p-dopant was used. A photoluminescence excitation mapping under different titration conditions provided more insight into the doping level of the tubes relative to their diameters, chiralities, and redox potentials. We proposed a mechanism for the CPE process. The semiconducting and metallic tubes are separated because of their different solubilities, which are determined by the bundling energy between the tubes and are related to their doping level in polymer solutions.Peer reviewed: YesNRC publication: Ye