Into the unknown

Peer reviewed: NoNRC publication: Ye

Clicks from space

Peer reviewed: NoNRC publication: Ye

One of the oldest stars?

Peer reviewed: NoNRC publication: Ye

Extensive deep neural networks for transferring small scale learning to large scale systems

We present a physically-motivated topology of a deep neural network that can efficiently infer extensive parameters (such as energy, entropy, or number of particles) of arbitrarily large systems, doing so with O(N) scaling. We use a form of domain decomposition for training and inference, where each sub-domain (tile) is comprised of a non-overlapping focus region surrounded by an overlapping context region. The size of these regions is motivated by the physical interaction length scales of the problem. We demonstrate the application of EDNNs to three physical systems: the Ising model and two hexagonal/graphene-like datasets. In the latter, an EDNN was able to make total energy predictions of a 60 atoms system, with comparable accuracy to density functional theory (DFT), in 57 milliseconds. Additionally EDNNs are well suited for massively parallel evaluation, as no communication is necessary during neural network evaluation. We demonstrate that EDNNs can be used to make an energy prediction of a two-dimensional 35.2 million atom system, over 1.0 \u3bcm\ub2 of material, at an accuracy comparable to DFT, in under 25 minutes. Such a system exists on a length scale visible with optical microscopy and larger than some living organisms.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

Quality assessment of bulk Boron nitride nanotubes for advancing research, commercial and industrial applications

Evaluating the quality of nanomaterials is essential for both basic research and industrial applications. Here, we describe a methodology for assessment of relative quality of boron nitride nanotube (BNNT) materials by absorption spectroscopy of regionrandom poly(3-hexyl-thiophene) (rra-P3HT) aggregates on BNNTs dispersed in chloroform. The strong selective \uf070\u2013\uf070 interaction between rra-P3HT and nanotubes combined with distinctive visual and spectroscopic changes allows a practical procedure for relative evaluation of BNNT external surface area and surface quality. The method calls first for the identification of the sample-specific polymer loading saturation point, which corresponds to the maximum BNNT surface polymer coverage in the sample. The sample quality (defined as the combination of sample purity and BNNT wall defect density) is determined from the structure and intensity of the absorption spectrum, which depend on the morphology and the total amount of rra-P3HT adsorbed on BNNT samples. This methodology for quality assessment is critical for accelerating the development of new, efficient purification strategies for bulk BNNT materials and advancing the investigation of BNNT properties and industrial applications.Peer reviewed: YesNRC publication: Ye

Quantitation of selenomethionine in multivitamins and selenium supplements by high performance liquid chromatography inductively-coupled plasma mass spectrometry

VITA-1 and VITB-1 multivitamin and mineral supplement candidate reference materials from the National Research Council Canada were analyzed for their total selenium and selenomethionine contents. Following a methanesulfonic acid reflux to extract selenomethionine from the selenized yeast in the multivitamins, analysis by high-performance liquid chromatography-inductively coupled plasma triple quadrupole mass spectrometry resulted in concentrations of 7.4 \ub1 3.0 \u3bcg SeMet g\u20131 and 16.4 \ub1 6.5 \u3bcg SeMet g 121 in VITA-1 and VITB-1, respectively. Twelve commercially available multivitamins and selenium supplements were analyzed following the same protocol. Seven of these were noted to contain 85\u2013115% of the selenium stated on the label; the others ranged from 5 to 147% of the claimed amount. Only one multivitamin contained selenomethionine at a concentration above the detection limit, but the amount found in the selenium supplements matched the label claims within a reasonable level of uncertainty. For comparison, two certified reference materials\u2014wheat gluten and egg powder, both certified for total selenium only\u2014were also examined and it was determined that selenomethionine accounted for 58% and 25% of the selenium in these food products, respectively.Peer reviewed: YesNRC publication: Ye

Fractal dimension and directional analysis of elastic and collagen fiber arrangement in unsectioned arterial tissues affected by atherosclerosis and aging

Structural proteins like collagen and elastin are major constituents of the extracellular matrix (ECM). ECM degradation and remodeling in diseases significantly impact the microorganization of these structural proteins. Therefore, tracking the changes of collagen and elastin fiber morphological features within ECM impacted by disease progression could provide valuable insight into pathological processes such as tissue fibrosis and atherosclerosis. Benefiting from its intrinsic high-resolution imaging power and superior biochemical specificity, nonlinear optical microscopy (NLOM) is capable of providing information critical to the understanding of ECM remodeling. In this study, alterations of structural fibrillar proteins such as collagen and elastin in arteries excised from atherosclerotic rabbits were assessed by the combination of NLOM images and textural analysis methods such as fractal dimension (FD) and directional analysis (DA). FD and DA were tested for their performance in tracking the changes of extracellular elastin and fibrillar collagen remodeling resulting from atherosclerosis progression/aging. Although other methods of image analysis to study the organization of elastin and collagen structures have been reported, the simplified calculations of FD and DA presented in this work prove that they are viable strategies for extracting and analyzing fiber-related morphology from disease-impacted tissues. Furthermore, this study also demonstrates the potential utility of FD and DA in studying ECM remodeling caused by other pathological processes such as respiratory diseases, several skin conditions, or even cancer.Peer reviewed: YesNRC publication: Ye

Fault diagnosis in chemical processes based on class-incremental FDA and PCA

A class-incremental scheme of fisher discriminant analysis is proposed to improve the performance ofprocess fault diagnosis. Fisher discriminant analysis seeks directions which are efficient for discrimination and has excellent fault detection and diagnostic performance for the sample set with the tag. However, due to the property of the model, it has no detection and diagnostic capabilities forun-seen faults. In order to address this issue, the $F$ direction, which is based on a partial $F$ -values with the principle component analysis, is proposed in this paper. After a new fault being detected and added into the known fault collection, a class-incremental scheme is used to update the fisher discriminant analysis model to enhance the model's ability for continuous fault identification. The proposed approach is validated by the Tennessee Eastman process for the fault diagnosis. The results demonstrate that the proposed class-incremental fisher discriminant analysis method outperforms other conventional fisher discriminant analysis methods.Peer reviewed: YesNRC publication: Ye

Genetics behind the biosynthesis of nonulosonic acid-containing lipooligosaccharides in Campylobacter coli

Campylobacter jejuni and Campylobacter coli are the most common causes of bacterial gastroenteritis in the world. Ganglioside mimicry by C. jejuni lipooligosaccharide (LOS) is the triggering factor of Guillain-Barr\ue9 syndrome (GBS), an acute polyneuropathy. Sialyltransferases from glycosyltransferase family 42 (GT-42) are essential for the expression of ganglioside mimics in C. jejuni. Recently, two novel GT-42 genes, cstIV and cstV, have been identified in C. coli. Despite being present in 3c11% of currently available C. coli genomes, the biological role of cstIV and cstV is unknown. In the present investigation, mutation studies with two strains expressing either cstIV or cstV were performed and mass spectrometry was used to investigate differences in the chemical composition of LOS. Attempts were made to identify donor and acceptor molecules using in vitro activity tests with recombinant GT-42 enzymes. Here we show that CstIV and CstV are involved in C. coli LOS biosynthesis. In particular, cstV is associated with LOS sialylation, while cstIV is linked to the addition of a diacetylated nonulosonic acid residue.Peer reviewed: YesNRC publication: Ye