An impedimetric biosensor for E. coli O157:H7 based on the use of\ua0self-assembled gold nanoparticles and protein G

Two kinds of electrochemical impedimetric biosensors for the detection of E. coli O157:H7 are described and compared. They were fabricated using self-assembled layers of thiolated protein G (PrG-thiol) on (i) planar gold electrodes and (ii) gold nanoparticles (Au NPs) modified gold electrodes. The fabrications of the biosensors were characterized using cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy and atomic force microscopy techniques. The modification of the planar gold electrode by Au NPs via self-assembled monolayer of 1,6-hexadithiol as a linker molecule increased the electrochemically active surface area by about 2.2 times. The concentration of PrG-thiol and its incubation time, as well as the concentration of IgG were optimized. The Au NP-based biosensor exhibited a limit of detection of 48 colony forming unit (cfu mL 121) which is 3 times lower than that of the planar gold electrode biosensor (140 cfu mL 121). It also showed a wider dynamic range (up to 107 cfu mL 121) and sensitivity. The improved analytical performance of the Au NP-modified biosensor is ascribed to the synergistic effect between the Au NPs and the PrG-thiol scaffold. The biosensor exhibited high selectivity for E. coli O157:H7 over other bacteria such as Staphylococcus aureus and Salmonella typhimurium.Peer reviewed: YesNRC publication: Ye

A rapid and sensitive method for the determination of inorganic chloride in oil samples

A novel isotope dilution method for the analysis of inorganic chloride in fuel oil matrix is presented. The samples were diluted by isopropyl alcohol:toluene, mixed with 37Cl 12 internal standard and reacted with triethyloxonium tetrafluoroborate at room temperature. This reagent promoted conversion of Cl 12 into stable ethyl chloride (EtCl) which was selectively detected by headspace GC\u2013MS/MS with no matrix effects. A limit of detection of 0.2\u202fmg\u202fkg 121 Cl 12 was obtained in fuel oil. The method was tested on the NIST SRM 1634c (trace elements in residual fuel oil) and validated through a series of robustness tests. Over 18 days, the variation in the signal response was less than 10% and the RSD for quantitative isotope dilution results was below 3%. Overall, the method is fast, simple and allows robust quantitation of inorganic chloride directly in the non-aqueous media.Peer reviewed: YesNRC publication: Ye

Advances in novel vaccines for foot and mouth disease: focus on recombinant empty capsids

Foot and mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals, which causes severe economic losses in the livestock industry. Currently available vaccines are based on inactivated FMD virus (FMDV). Although inactivated virus vaccines have proved to be effective in FMD control, they have a number of disadvantages, including the need for high bio-containment production facilities and the lack of induction of immunological memory. Novel FMD vaccines based on the use of recombinant empty capsids have shown promising results. These recombinant empty capsids are attractive candidates because they avoid the use of virus in the production facilities but conserve its complete repertoire of conformational epitopes. However, many of these recombinant empty capsids require time-consuming procedures that are difficult to scale up. Achieving production of a novel and efficient FMD vaccine requires not only immunogenic antigens, but also industrially relevant processes. This review intends to summarize and compare the different strategies already published for the production of FMDV recombinant empty capsids, focusing on large-scale production.Peer reviewed: YesNRC publication: Ye

An augmented reality sign-reading assistant for users with reduced vision

People typically rely heavily on visual information when finding their way to unfamiliar locations. For individuals with reduced vision, there are a variety of navigational tools available to assist with this task if needed. However, for wayfinding in unfamiliar indoor environments the applicability of existing tools is limited. One potential approach to assist with this task is to enhance visual information about the location and content of existing signage in the environment. With this aim, we developed a prototype software application, which runs on a consumer head-mounted augmented reality (AR) device, to assist visually impaired users with sign-reading. The sign-reading assistant identifies real-world text (e.g., signs and room numbers) on command, highlights the text location, converts it to high contrast AR lettering, and optionally reads the content aloud via text-to-speech. We assessed the usability of this application in a behavioral experiment. Participants with simulated visual impairment were asked to locate a particular office within a hallway, either with or without AR assistance (referred to as the AR group and control group, respectively). Subjective assessments indicated that participants in the AR group found the application helpful for this task, and an analysis of walking paths indicated that these participants took more direct routes compared to the control group. However, participants in the AR group also walked more slowly and took more time to complete the task than the control group. The results point to several specific future goals for usability and system performance in AR-based assistive tools.Peer reviewed: YesNRC publication: Ye

Discovery of a new natural product and a deactivation of a quorum sensing system by culturing a \u201cproducer\u201d bacterium with a heat-killed \u201cinducer\u201d culture

Herein we describe a modified bacterial culture methodology as a tool to discover new natural products via supplementing actinomycete fermentation media with autoclaved cultures of \u201cinducer\u201d microbes. Using seven actinomycetes and four inducer microbes, we detected 28 metabolites that were induced in UHPLC-HRESIMS-based analysis of bacterial fermentations. Metabolomic analysis indicated that each inducer elicited a unique response from the actinomycetes and that some chemical responses were specific to each inducer-producer combination. Among these 28 metabolites, hydrazidomycin D, a new hydrazide-containing natural product was isolated from the pair Streptomyces sp. RKBH-B178 and Mycobacterium smegmatis. This result validated the effectiveness of the strategy in discovering new natural products. From the same set of induced metabolites, an in-depth investigation of a fermentation of Streptomyces sp. RKBH-B178 and autoclaved Pseudomonas aeruginosa led to the discovery of a glucuronidated analog of the pseudomonas quinolone signal (PQS). We demonstrated that RKBH-B178 is able to biotransform the P. aeruginosa quorum sensing molecules, 2-heptyl-4-quinolone (HHQ), and PQS to form PQS-GlcA. Further, PQS-GlcA was shown to have poor binding affinity to PqsR, the innate receptor of HHQ and PQS.Peer reviewed: YesNRC publication: Ye

The effect of viscosity on free surface flow inside an angularly oscillating rectangular tank

This paper presents a three-dimensional solution algorithm for solving free surface flows including the effect of near wall viscous dissipation. Slip boundary conditions that could take into account the viscous shear at the boundary are proposed in a context that is well suited to free surface flow applications. The proposed finite element method uses a Level-Set formulation on fixed meshes and, consequently, the liquid/gas interface is generally located inside mesh elements. Standard interpolation of flow variables inside partially filled elements leads to an inappropriate treatment of gravity forces, pressure gradient and inertia which can generate spurious oscillations. To alleviate these issues, we use enriched shape functions for the pressure that introduce a discontinuity in the normal pressure gradient at the interface. The additional pressure degree of freedom is eliminated at the elementary system level by static condensation thus having no impact on the structure of the linear system matrix. This approach is well-suited for gravity-driven free surface problems such as violent sloshing inside tanks. The algorithm is first verified and validated on simpler problems for which analytical or experimental results are available. Then it is applied to the study of sloshing where it is validated against a robust set of experiment from Delorme et al. [1] and Souto-Iglesias et al. [2, 3] for the water and oil flow inside an angularly oscillating rectangular tank. The proposed approach to include viscous dissipation at the wall proves to be very effective in capturing the significant differences in flow dynamics between the two liquids having different viscosities. Moreover, the enriched pressure shape functions results in stable, oscillation free solution thus representing an efficient way to accurately solve complex gravity-driven free surface problems without requiring re-meshing or mesh refinement.Peer reviewed: YesNRC publication: Ye

Feasibility of a microalgal wastewater treatment for the removal of nutrients under non-sterile conditions and carbon limitation

Microalgal treatment of municipal wastewater has been discussed as a novel strategy for the removal of excess nutrients and metals. Additionally, a number of products can be obtained from the resulting microalgal biomass, including energy products that can be utilized within the treatment plant. However, the effectiveness of these microalgal systems can be significantly affected by the natural biota, which could consequently impact the quality of the wastewater effluent. This study evaluated the performance of two microalgal species in the removal of nutrients from non\u2010sterile, highly concentrated synthetic wastewater. The results showed that monocultures of Scenedesmus sp. AMDD and Chlorella sorokiniana could remove up to 60\u2009% NH4+, and 44 and 35\u2009% PO43\u2010, respectively, in a semi\u2010continuous cultivation mode without negatively affecting effluent quality.Peer reviewed: YesNRC publication: Ye

Manipulating redox conditions to enhance in situ bioremediation of RDX in groundwater at a contaminated site

Surficial application of waste glycerol (WG) for enhanced bioremediation was tested in situ at an old military range site to address hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) contaminated groundwater. This treatment was effective in inducing strong reducing conditions (range: 124 to 12205\u202fmV) and increasing the concentrations of organic carbon (from 10 to 729\u202fmg/L) and fatty acids (from 0 to 940\u202fmg/L) concomitantly with a decrease in RDX concentrations (range: 17 to 143\u202f\u3bcg/L) to below detection limits (0.1\u202f\u3bcg/L) in 2 of the 3 monitoring wells (MWs) evaluated. None of these changes were observed in the control MW. RDX disappeared without the detection of any common anaerobic nitroso degradation intermediates, with the exception of one MW where the concentration of organics did not significantly increase (range: 10 to 20\u202fmg/L), suggesting the conditions were not favourable for biodegradation. Ecotoxicological analysis suggested that the use of WG may have some dose-related deleterious effects on different soil and aquatic receptors. Analysis of the microbial community composition, using 16S rRNA gene amplicon sequences, which provided insight into whether the process design had selected for and stimulated the optimal microbial populations, indicated co-existence of numerous Operational Taxonomic Units (OTUs) belonging to groups known to be capable of RDX degradation under anaerobic conditions, with a positive link between Geobacter spp. enrichment and the presence of RDX nitroso metabolites. Overall, the results from this field test show that this treatment process can provide an effective long-term, semi-passive remediation option for RDX contaminated groundwater.Peer reviewed: YesNRC publication: Ye

Atlantic Canadian Cyanobacterial Workshop 2018: workshop final report

The last few summers have seen an unprecedented rise in the occurrence and impact of cyanobacterial blooms in the lakes and rivers of Atlantic Canada. These have already affected recreational waters, harmed pets and will cause ongoing issues as they reoccur in the region over the coming years. The main goal of the Atlantic Canadian Cyanobacterial Workshop (ACCW) was to bring together the diverse group of stakeholders involved in monitoring, managing or studying cyanobacteria and their toxins in Atlantic Canada so as to build awareness of emerging needs and existing expertise in the region. By increasing awareness of common challenges and existing capabilities a foundation can be developed for ongoing discussion and collaboration that will be needed to effectively manage the issue going forward.Peer reviewed: NoNRC publication: Ye

Bragg filter bandwidth engineering in subwavelength grating metamaterial waveguides

Bragg gratings are fundamental building blocks for integrated photonic circuits. In the high-index contrast silicon-on-insulator material platform, it is challenging to accurately control the grating strength and achieve narrow spectral bandwidths. Here we demonstrate a novel Bragg grating geometry utilizing a silicon subwavelength grating (SWG) waveguide with evanescently coupled periodic Bragg loading segments placed outside the SWG core. We report experimental 3 dB filter bandwidths in a range from 8 nm to 150 pm by adjusting the distance of the Bragg loading segments from the core and the relative phase shift of the segments on the two sides of the waveguide, with a structure that has a minimum feature size of 100 nm.Peer reviewed: YesNRC publication: Ye