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Analysis of O-Acetylated sialic acids in dried blood spots
No full textSialic acid is a family of N- and O-substitutions of neuraminic acid. Plasma or serum sialic acid has been established as a potential disease marker. For example, the presence of 9-O-acetyl on the sialic acid of some glycans and glycoconjugates (e.g., 9-O-acetyl GD3 ganglioside) could be related to cancer occurrence. A variety of assays are available to measure serum or plasma sialic acid; however, sample preparation and storage can alter the O-acetylation profile due to the loss of O-acetyl groups and/or the migration of O-acetyl groups. Herein, we report dried blood spot (DBS) sampling, in combination with diamino-4,5-methylenedioxybenzene derivatization, for profiling sialic acids in blood samples with minimal alteration in O-acetylation patterns. The feasibility of the method was first evaluated by analyzing sialic acids in crucian carp blood and comparing with traditional blood/plasma sample preparation procedures. A total of 19 different sialic acids were identified by using liquid chromatography\u2013Orbitrap mass spectrometry, including four mono-O-acetylated N-acetylneuraminic acids, four mono-O-acetylated N-glycolylneuraminic acids, six di-O-acetylated N-acetylneuraminic acids, and three tri-O-acetylated N-acetylneuraminic acids. The long-term storage study indicated that DBS sampling could effectively preserve the O-acetylation information for at least 6 weeks. Thus, it is demonstrated that this method is a valuable tool for the study of sialic acid diversity, especially for the characterization of isomeric structures.Peer reviewed: YesNRC publication: Ye
Development of a multiaxis active seat mount to mitigate helicopter aircrew whole-body vibration exposure
No full textThis article presents the development and evaluation of a proof-of-concept multiaxis and actively controlled helicopter seat mount for aircrew whole-body vibration reduction. The multiaxis seat mount is designed to be installed between the helicopter seat floor and the seat supporting structure to minimize the impact on crashworthiness requirements of the helicopter seat. The design involves multiple miniature force actuators to counteract the vibrations of the seat frame and occupant transmitted from the helicopter floor in three orthogonal directions. The actuators are controlled by an adaptive feedforward filtered-x least mean square algorithm to cancel the helicopter floor vibration input. The prototype active seat mount design was tested in various configurations with a shaker table providing representative Bell-412 helicopter vibration inputs. Test results demonstrated that the vibrations of the seat frame and mannequin occupant body were suppressed simultaneously, and the major N/rev harmonic peaks of the occupant\u2019s whole-body vibration were reduced by more than 20\u2009dB. This demonstrated that the multiaxis active seat mount design can mitigate the whole-body vibration exposure of the helicopter aircrew to improve their ride quality and reduce adverse health effect.Peer reviewed: YesNRC publication: Ye
High-precision measurements of the isotopic composition of common lead using MC-ICPMS: comparison of calibration strategies based on full gravimetric isotope mixture and regression models
No full textThe determination of isotope ratios of lead finds many important applications in earth and planetary sciences. In this study, we report the first independent and fully calibrated absolute isotope ratio measurements of a common lead since the seminal work by the NIST in the 1960s, which has provided the widely used standards SRM 981 and SRM 982. This work employs MC-ICPMS for the absolute isotope ratio measurements, which were calibrated using two independent methods: the full gravimetric isotope mixture method based on the use of all four near-pure lead isotopes (the first application of this primary method to lead) and the regression method with NIST SRM 997 thallium isotopic standard as the primary calibrator. Both calibration methods provide results consistent to a few parts in 104, which were used to characterize isotope ratios of lead in an NRC candidate reference material, high-purity common lead HIPB-1.Peer reviewed: YesNRC publication: Ye
Evaluating the standby power consumption of smart LED bulbs
No full textThere is an increasing demand for smart devices in recent years. One of the latest additions to the long list of these smart devices is the smart light-emitting diode (LED) light sources. They offer many additional features in addition to provide light. However, like all other smart devices, when they are turned off by the user through a smart device, they still consume energy. That standby power consumption, when the bulbs are off, soon becomes an increasing load to the grid. In this study, we investigated the current smart residential LED bulb market and selected three samples from 30 models that are available to Canadian consumers. We tested the standby power consumption of those samples by following the IEC 62301 standard. The results showed that the standby power consumption of 21 Smart LED bulb models (out of 30) was less than 0.5\u202fW, which resembles the maximum allowable standby power consumption amount of a smart LED bulb, if the manufacturers intend to carry the Energy Star logo on their product. Although most products are not Energy Star rated, it is a promising result. We also found that the standby power consumption of the three bulb samples tested for each model was generally consistent (the standard deviation was less than 0.02). Only three models had one sample measured with a higher or lower consumption than the other two samples (highest difference 0.43\u202fW, lowest difference: 0.06\u202fW, standard deviation higher than 0.03). This internal consistency or standby power consumption amount in between samples are worrisome. Although our sample size was small, we believe that the findings from our study enabled to gather enough information to have a basic idea about the status of current standby power consumption of the smart LED bulbs in Canadian residential market.Peer reviewed: YesNRC publication: Ye
Quantification of amine functional groups on silica nanoparticles: a multi-method approach
No full textSurface chemistry is an important factor for quality control during production of nanomaterials and for controlling their behavior in applications and when released into the environment. Here we report a comparison of four methods for quantifying amine functional groups on silica nanoparticles (NPs). Two colorimetric assays are examined, ninhydrin and 4-nitrobenzaldehyde, which are convenient for routine analysis and report on reagent accessible amines. Results from the study of a range of commercial NPs with different sizes and surface loadings show that the assays account for 50\u2013100% of the total amine content, as determined by dissolution of NPs under basic conditions and quantification by solution-state \ub9H NMR. To validate the surface quantification by the colorimetric assays, the NPs are modified with a trifluoromethylated benzaldehyde probe to enhance sensitivity for quantitative \ub9\u2079F solid state NMR and X-ray photoelectron spectroscopy (XPS). Good agreement between the assays and the determination from solid-state NMR is reinforced by elemental ratios from XPS, which indicate that in most cases the difference between total and accessible amine content reflects amines that are outside the depth probed by XPS. Overall the combined results serve to validate the relatively simple colorimetric assays and indicate that the reactions are efficient at quantifying surface amines, by contrast to some other covalent modifications that have been employed for functional group quantification.Peer reviewed: YesNRC publication: Ye
An extension of adaptive multi-start tabu search for the maximum quasi-clique problem
No full textGiven a simple undirected graph G=(V,E) and real constant (threshold) \u3b3 08(0,1], a subset of vertices S 86V is a \u3b3-quasi-clique (\u3b3-clique) if the number of edges in the subgraph induced by S is at least equal to \u3b3|S|2. The Maximum \u3b3-Quasi-Clique Problem (MQCP) aims to find a \u3b3-quasi-clique of maximum cardinality and it was shown to be NP-hard. The MQCP has numerous applications in several real-life networks including social, biological, transportation, internet and communication networks. This paper proposes an extension of Tabu Search approach (TSQC) for solving the maximum Quasi-Clique problem. TSQC is an extension of Adaptive Multistart Tabu Search (AMTS) method given by Wu and Hao (2013) for solving the maximum clique problem (MCP). The TSQC algorithm is evaluated on DIMACS and BHOSLIB benchmark instances of the maximum clique problem and on real-life networks and compared with the most recent exact and heuristic methods. Computational results disclose that the TSQC algorithm reaches the largest known quasi-clique in a reasonable time on the real-life networks and it outperforms the existing methods on DIMACS and BHOSLIB instances. Moreover, our proposed algorithm gives some new results with improved quality of MQCP.Peer reviewed: YesNRC publication: Ye