740 research outputs found
Cha guan. [3 & 4]
No full text1. 茶館 : side 3 -- 2. 茶館 : side 4.Section number supplied by cataloguer.Possibly reproduced from other commercial recording or radio broadcast (Pending for review)Electronic reproduction from Rulan Chao Pian Audio Cassette Collection.Spoken in Chinese.1. Cha guan : side 3 -- 2. Cha guan : side 4
Cha guan. [1 & 2]
No full text1. 茶館 : side 1 -- 2. 茶館 : side 2.Section number supplied by cataloguer.Possibly reproduced from other commercial recording or radio broadcast (Pending for review)Electronic reproduction from Rulan Chao Pian Audio Cassette Collection.Spoken in Chinese.1. Cha guan : side 1 -- 2. Cha guan : side 2
COMPLEXITIES OF 3-MANIFOLDS FROM TRIANGULATIONS, HEEGAARD SPLITTINGS AND SURGERY PRESENTATIONS
No full textWe study complexities of 3-manifolds defined from triangulations, Heegaard splittings, and surgery presentations. We show that these complexities are related by linear inequalities, by presenting explicit geometric constructions. We also show that our linear inequalities are asymptotically optimal. Our results are used in another paper of the author to estimate Cheeger-Gromov L-2 rho-invariants in terms of geometric group theoretic and knot theoretic data.110sciescopu
Lean NOx Capture and Reduction by NH3 via NO+ Intermediates over H-CHA at Room Temperature
No full textThe oxidation of NO to NO2 and the subsequent reduction by NH3 via a NO+ intermediate over a proton-type chabazite zeolite (H-CHA) were investigated by the combination of in situ infrared (IR) spectroscopy and density functional theory (DFT) calculations. The in situ IR spectral results indicate that the NO' species formed under a flow of NO + O-2 at 27-250 degrees C are more stable at lower temperatures over both H-CHA and copper-cation-exchanged CHA zeolite (Cu-CHA). The Arrhenius plot (T = 27-120 degrees C) shows a negative apparent activation barrier energy (-11.5 kJ mol(-1)) for the formation of NO+ species under the NO + O(2 )flow over H-CHA. The time course of the IR spectra at 27 degrees C shows that NO is oxidized by O-2 to NO2 and then further converted via N2O4 to NO+ and NO3. The subsequent exposure to NH3 at 27 degrees C reduces the NO species to N-2. DFT calculations revealed that Bronsted acid sites in zeolite pores promote the dissociation of N2O4 intermediates into NO and NO3- species with a low activation barrier (15 kJ mol(-1)). Moreover, the computed activation barrier for the reduction of NO+ species by NH3 was considerably low (6 kJ mol(-1)). The experimental and theoretical results of this study demonstrate the high potential of Cu-free H-CHA zeolites for promoting lean NOx capture to form NO+ species and the subsequent reduction by NH3 at room temperature
Amenable L-2-Theoretic Methods and Knot Concordance
No full textWe reveal new structures in the topological knot concordance group. As a key ingredient, we develop obstructions using L-2-theoretic methods for amenable groups in Strebel's class recently introduced by Orr and the author. Concerning (h)-solvable knots, which are defined in terms of certain Whitney towers of height h in bounding 4-manifolds, we show the following: for any n>1, there are (n)-solvable but non-(n. 5)-solvable (and therefore nonslice) knots, which are not detected by prior methods using Cochran-Orr-Teichner L-2-signature obstructions as well as Levine algebraic obstructions and Casson-Gordon invariants.X1197sciescopu
Ataxin-2 Dysregulation Triggers a Compensatory Fragile X Mental Retardation Protein Decrease in Drosophila C4da Neurons
No full textDendrites require precise and timely delivery of protein substrates to distal areas to ensure the correct morphology and function of neurons. Many of these protein substrates are supplied in the form of ribonucleoprotein (RNP) complex consisting of RNA-binding proteins (RBPs) and mRNAs, which are subsequently translated in distal dendritic areas. It remains elusive, however, whether key RBPs supply mRNA according to local demands individually or in a coordinated manner. In this study, we investigated how Drosophila sensory neurons respond to the dysregulation of a disease-associated RBP, Ataxin-2 (ATX2), which leads to dendritic defects. We found that ATX2 plays a crucial role in spacing dendritic branches for the optimal dendritic receptive fields in Drosophila class IV dendritic arborization (C4da) neurons, where both expression level and subcellular location of ATX2 contribute significantly to this effect. We showed that translational upregulation through the expression of eukaryotic translation initiation factor 4E (eIF4E) further enhanced the ATX2-induced dendritic phenotypes. Additionally, we found that the expression level of another disease-associated RBP, fragile X mental retardation protein (FMRP), decreased in both cell bodies and dendrites when neurons were faced with aberrant upregulation of ATX2. Finally, we revealed that the PAM2 motif of ATX2, which mediates its interaction with poly(A)-binding protein (PABP), is potentially necessary for the decrease of FMRP in certain neuronal stress conditions. Collectively, our data suggest that dysregulation of RBPs triggers a compensatory regulation of other functionally-overlapping RBPs to minimize RBP dysregulation-associated aberrations that hinder neuronal homeostasis in dendrites. © The Korean Society for Molecular and Cellular Biology. All rights reserved.1
High-Silica CHA Zeolite Membrane with Ultra-High Selectivity and Irradiation Stability for Krypton/Xenon Separation
No full textCapture and storage of the long-lived 85Kr is an efficient approach to mitigate the emission of volatile radionuclides from the spent nuclear fuel reprocessing facilities. However, it is challenging to separate krypton (Kr) from xenon (Xe) because of the chemical inertness and similar physical properties. Herein we prepared high-silica CHA zeolite membranes with ultra-high selectivity and irradiation stability for Kr/Xe separation. The suitable aperture size and rigid framework endures the membrane a strong size-exclusion effect. The ultrahigh selectivity of 51–152 together with the Kr permeance of 0.7–1.3×10−8 mol m−2 s−1 Pa−1 of high-silica CHA zeolite membranes far surpass the state-of-the-art polymeric membranes. The membrane is among the most stable polycrystalline membranes for separation of humid Kr/Xe mixtures. Together with the excellent irradiation stability, high-silica CHA zeolite membranes pave the way to separate radioactive Kr from Xe for a notable reduction of the volatile nuclear waste storage volume.ChemE/Catalysis Engineerin
Local structure and NO adsorption/desorption property of Pd2+ cations at different paired Al sites in CHA zeolite
No full textRecently, Pd-exchanged CHA zeolites (Pd-CHA) have attracted attention as promising passive NOx adsorbers (PNAs) for reducing NOx emissions during the cold start period of a vehicle engine. In this work, the relationship between the local structures and the NO adsorption/desorption properties of the Pd cations in CHA zeolites was investigated. Pd cation formation and NO adsorption were theoretically explored by density functional theory (DFT) calculations for different paired Al sites in six-/eight-membered rings (6MR/8MR). Furthermore, we prepared a series of Pd-CHAs with different Pd loadings (0.5-5.4 wt%) and evaluated their NO adsorption/desorption properties by in situ infrared (IR) spectroscopy and temperature-programmed desorption (TPD) measurements. The increase in the Pd loading resulted in a shift in the NO desorption temperature toward a higher temperature regime. This phenomenon was ascribed to the increase in the proportion of less stable Pd cations, resulting in improved NO adsorption. Furthermore, the effect of Al distribution on the NO adsorption property of Pd-CHA was examined using CHA zeolites containing different proportions of paired Al sites in 6MR while maintaining similar Si/Al ratios (Si/Al = 12.0-16.5). The present study, based on a combination of theoretical and experimental techniques, shows that the NO adsorption/desorption properties over Pd-CHA can be tuned by controlling the Pd loading amount and the type of paired Al sites
2018 CHA Prizes / Prix 2018 de la SHC
No full textThe CHA is pleased to inform its members of the 2018 shortlists
for its Sir John A. Macdonald Prize, given to the non-fiction
work of Canadian history judged to have made the most significant
contribution to the understanding of the Canadian past,
the prize is sponsored by Manulife Financial in the amount of
$5,000; and the Wallace K. Ferguson Prize, which recognizes the
outstanding scholarly book in a field of history other than Canadian
history. There prizes will be announced at the CHA Annual
Meeting at the University of Regina on Tuesday, May 29. This
year’s shortlisted books are (in alphabetical order by author)
Unknotted gropes, Whitney towers, and doubly slicing knots
No full textWe study the structure of the exteriors of gropes and Whitney towers in dimension 4, focusing on their fundamental groups. In particular we introduce a notion of unknottedness of gropes and Whitney towers in the 4-sphere. We prove that various modifications of gropes and Whitney towers preserve the unknottedness and do not enlarge the fundamental group. We exhibit handlebody structures of the exteriors of gropes and Whitney towers constructed by earlier methods of Cochran, Teichner, Horn, and the first author and use them to construct examples of unknotted gropes and Whitney towers. As an application, we introduce geometric bi-filtrations of knots which approximate the double sliceness in terms of unknotted gropes and Whitney towers. We prove that the bi-filtrations do not stabilize at any stage.11Nsciescopu
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