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Arabidopsis UBC13 differentially regulates two programmed cell death pathways in responses to pathogen and low-temperature stress
No full text-UBC13 is required for Lys63\u2010linked polyubiquitination and innate immune responses in mammals, but its functions in plant immunity remain to be defined. -Here we used genetic and pathological methods to evaluate roles of Arabidopsis UBC13 in response to pathogens and environmental stresses. -Loss of UBC13 failed to activate the expression of numerous cold\u2010responsive genes and resulted in hypersensitivity to low\u2010temperature stress, indicating that UBC13 is involved in plant response to low\u2010temperature stress. Furthermore, the ubc13 mutant displayed low\u2010temperature\u2010induced and salicylic acid\u2010dependent lesion mimic phenotypes. Unlike typical lesion mimic mutants, ubc13 did not enhance disease resistance against virulent bacterial and fungal pathogens, but diminished hypersensitive response and compromised effector\u2010triggered immunity against avirulent bacterial pathogens. UBC13 differently regulates two types of programmed cell death in response to low temperature and pathogen. The lesion mimic phenotype in the ubc13 mutant is partially dependent on SNC1. UBC13 interacts with an F\u2010box protein CPR1 that regulates the homeostasis of SNC1. However, the SNC1 protein level was not altered in the ubc13 mutant, implying that UBC13 is not involved in CPR1\u2010regulated SNC1 protein degradation. -Taken together, our results revealed that UBC13 is a key regulator in plant response to low temperature and pathogens.Peer reviewed: YesNRC publication: Ye
Laser-induced breakdown spectroscopy of molten matte
No full textLaser-induced breakdown spectroscopy (LIBS) is an atomic emission spectroscopy technique suitable for in-situ and in-line measurements during pyrometallurgy. A mobile prototype system was developed to measure elemental compositions of molten metals. An inert gas flows through a tube with its end immersed in molten metal and the gas bubbles out below the melt surface. The LIBS measurement is made through the tube and onto the bubble\u2019s surface. This avoids measuring surface contaminants and slag. This paper presents the simultaneous measurement of Cu, Ni, Fe, Co, and S concentrations in molten matte at 1,125\ub0C.Peer reviewed: YesNRC publication: Ye
A novel human induced pluripotent stem cell blood-brain barrier model: applicability to study antibody-triggered receptor-mediated transcytosis
No full textWe have developed a renewable, scalable and transgene free human blood-brain barrier model, composed of brain endothelial cells (BECs), generated from human amniotic fluid derived induced pluripotent stem cells (AF-iPSC), which can also give rise to syngeneic neural cells of the neurovascular unit. These AF-iPSC-derived BECs (i-BEC) exhibited high transendothelial electrical resistance (up to 1500\u2009\u3a9 cm2) inducible by astrocyte-derived molecular cues and retinoic acid treatment, polarized expression of functional efflux transporters and receptor mediated transcytosis triggered by antibodies against specific receptors. In vitro human BBB models enable pre-clinical screening of central nervous system (CNS)-targeting drugs and are of particular importance for assessing species-specific/selective transport mechanisms. This i-BEC human BBB model discriminates species-selective antibody- mediated transcytosis mechanisms, is predictive of in vivo CNS exposure of rodent cross-reactive antibodies and can be implemented into pre-clinical CNS drug discovery and development processes.Peer reviewed: YesNRC publication: Ye
Genetic characterization of type II Fusarium head blight resistance derived from transgressive segregation in a cross between Eastern and Western Canadian spring wheat
No full textFusarium head blight (FHB) caused by Fusarium graminearum is a devastating disease affecting global wheat production, causing significant losses to yield and grain quality. The Eastern Canadian line FL62R1 was developed using a systemic breeding approach and boasts high levels of FHB resistance with good yield, desirable agronomics, and end-use quality traits. The objective of this study was to identify genetic determinants of type II resistance in a cross between FL62R1 and cv. Stettler, a Canada Western Red Spring variety rated moderately susceptible to FHB. Although neither parent displayed strong resistance to FHB spread within spikes following point inoculation (type II resistance) in greenhouses, strong type II resistance was observed in a large number of progeny, including 6% with resistance comparable to the best check line, Sumai 3. Quantitative trait locus (QTL) mapping identified a locus from chromosome 2BL of Stettler which provides Sumai 3 level type II resistance when combined with favorable FHB resistance QTLs with minor effects from FL62R1. This study provides insight into transgressive segregation for FHB, which despite its importance is poorly understood, rare, and difficult to predict. It also begins to dissect the genetic architecture of FHB resistance in wheat derived from the systemic breeding approach.Peer reviewed: YesNRC publication: Ye
Radical-initiated and thermally induced hydrogermylation of alkenes on the surfaces of germanium nanosheets
No full textThe synthesis of germanium nanomaterials with well-defined surface chemistry is of considerable interest because of not only general scientific curiosity but also their vast potential in optoelectronics, energy storage, and the semiconductor industry. Herein, we report a straightforward preparative route that yields hydride-terminated germanium nanosheet (H-GeNS) monolayers via sonochemical exfoliation of hydride-terminated germanane flakes (HGe-flakes) derived from crystalline CaGe2. We subsequently show that these freestanding H-GeNSs are readily functionalized by radical-initiated and thermally induced hydrogermylation. Furthermore, we demonstrate that following functionalization the crystal structure of the GeNSs remains intact, and the introduction of organic moieties to the GeNS surfaces imparts improved thermal stability and solvent compatibility.Peer reviewed: YesNRC publication: Ye
Copper ion assisted photochemical vapor generation of chlorine for its sensitive determination by sector field inductively coupled plasma mass spectrometry
No full textA novel, reliable, and sensitive approach for the determination of chlorine by sector field inductively coupled plasma mass spectrometry (SF-ICPMS) using photochemical vapor generation for sample introduction is presented. Methyl chloride is generated from different chlorine species in a flow-through photochemical reactor using a 1% solution of acetic acid containing 7.5 \u3bcg g\u20131 of Cu2+. The volatile product is directed by an argon carrier gas to a gas\u2013liquid separator and introduced into the instrument. A sample flow rate at 1.7 mL min\u20131 and a 45 s irradiation time provided a 74-fold enhancement in sensitivity compared to conventional nebulization. A blank-limited detection limit of 0.5 ng g\u20131 for chloride, suitable for quantitation at trace levels, was achieved. The proposed method was validated by analysis of two certified reference materials, NIST SRM 1568b rice flour and SRM 1571 orchard leaves, with satisfactory results, as well as three varieties of bottled water, achieving spike recoveries between 101% and 105%.Peer reviewed: YesNRC publication: Ye
Development of stabilized immersed boundary-body Conformal enrichment CFD model for freezing and melting
No full textNumerous processes in the automotive, additive manufacturing or energy storage industries require an accurate prediction of the solidification (freezing) and melting (thawing) dynamics of substances. The numerical modeling of these phase change is highly complex because it includes sharp moving interfaces and strong discontinuities in the material properties. This complexity is often exacerbated by the occurrence of natural convection, which induces a strong coupling between the motion of the liquid and the position of the solid-liquid interface. This leads to strongly coupled non-linear thermo-fluid problems which have to be solved in complex geometries. In this work, we introduce two novel stabilized finite element models to predict the phase change with natural convection. The first model uses a more classical viscosity approach to impose stasis in the solid region whereas the second one is based on an immersed boundary formulation to accurately describe the solid-fluid interface. The efficiency of the stabilized approach is first demonstrated by studying the Stefan problem. The two approaches to impose stasis are then compared using 2D test cases before they are both used to study melting in a rectangular (2D) and prismatic (3D) cavity. Significant differences are observed in the flow profiles and the solid-liquid interface between the 2D and the 3D simulations.Peer reviewed: YesNRC publication: Ye
Splitting-merging clustering algorithm for collaborative filtering recommendation system
No full textCollaborative filtering (CF) is a well-known and successful filtering technique that has its own limits, especially in dealing with highly sparse and large-scale data. To address this scalability issue, some researchers propose to use clustering methods like K-means that has the shortcomings of having its performances highly dependent on the manual definition of its number of clusters and on the selection of the initial centroids, which leads in case of ill-defined values to inaccurate recommendations and an increase in computation time. In this paper, we will show how the Merging and Splitting clustering algorithm can improve the performances of recommendation with reasonable computation time by comparing it with K-means based approach. Our experiment results demonstrate that the performances of our system are independent on the initial partition by considering the statistical nature of data. More specially, results in this paper provide significant evidences that the proposed splitting-merging clustering based CF is more scalable than the well-known K-means clustering based CF.Peer reviewed: YesNRC publication: Ye