• Title/Summary/Keyword: University of British Columbia

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Isoquinoline Alkaloids from Fumaria bastardii

  • Kucukboyaci, Nurgun;Bingol, Funda;Sener, Bilge;Kutney, James P.;Stoynov, Nikolay
    • Natural Product Sciences
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    • v.4 no.4
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    • pp.257-262
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    • 1998
  • The extract of the aerial parts of Fumaria bastardii Bor. afforded 12 alkaloids belonging to the skeletally six different groups of the isoquinoline alkaloids. In this publication, the isolation and identification of protopine (1), corydaldine (2), oxyhydrastinine (3), (-)-fumaritine (4), (+)-fumariline (5), (-)-O-methylfumarophycine (12), (+)-bicuculline (10), $(-)-{\beta}-hydrastine$ (7), (-)-corlumine (11), (+)-tetrahydropalmatine (8), (-)-stylopine (6), and (+)-juziphine (9) are described. Their structures have been determined by using extensive spectroscopic techniques. This is the first report of the occurrence of these alkaloids in Fumaria bastardii of Turkish origin.

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Seasonal Soil Temperature and Moisture Regimes in a Ginseng Garden

  • Bailey, W.G.;Stathers, R.J.;Dobud, A.G.
    • Journal of Ginseng Research
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    • v.12 no.1
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    • pp.53-62
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    • 1988
  • A field experiment was conducted in the arid interior of British Columbia, Canada to assess the seasonal soil temperature and moisture regimes in an American ginseng garden. As a consequence of the man-modified microclimate (elevated shade canopy and surface covering of mulch), the growing environment of the crop was fundamentally altered when compared to adjacent agricultural growing environments. In the ginseng garden, soil temperatures were found to remain low throughout the growing season whereas soil moisture remained high when compared with the outside garden environment. These results indicate that even in the hot, arid environment of the interior of British Columbia, the growing of ginseng is undertaken in sub-optimal conditions for the major part of the growing season. This poses challenges for the producers of the crop to modify the architecture of the gardens to enhance the soil regime without creating a deleterious aerial environment.

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Combined Relay Selection and Cooperative Beamforming for Physical Layer Security

  • Kim, Jun-Su;Ikhlef, Aissa;Schober, Robert
    • Journal of Communications and Networks
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    • v.14 no.4
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    • pp.364-373
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    • 2012
  • In this paper, we propose combined relay selection and cooperative beamforming schemes for physical layer security. Generally, high operational complexity is required for cooperative beamforming withmultiple relays because of the required information exchange and synchronization among the relays. On the other hand, while it is desirable to reduce the number of relays participating in cooperative beamforming because of the associated complexity problem, doing so may degrade the coding gain of cooperative beamforming. Hence, we propose combined relay selection and cooperative beamforming schemes, where only two of the available relays are selected for beamforming and data transmission. The proposed schemes introduce a selection gain which partially compensates for the decrease in coding gain due to limiting the number of participating relays to two. Both the cases where full and only partial channel state information are available for relay selection and cooperative beamforming are considered. Analytical and simulation results for the proposed schemes show improved secrecy capacities compared to existing physical layer security schemes employing cooperative relays.

Boron nitride based processing aids

  • Hatzikiriakos, Savvas G.;Rathod, Nimish
    • Korea-Australia Rheology Journal
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    • v.15 no.4
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    • pp.173-178
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    • 2003
  • Boron nitride is a new processing aid that is capable of eliminating gross melt fracture in several polymer processing operations. Its combinations with other processing aids i.e. fluoropolymers offer additional possibilities of obtaining enhanced processing aids that may take the processes to rates not realized before. A variety of different such combinations are discussed in this paper. The essential componenets are (1) boron nitride capable of eliminating gross melt fracture and (2) suitable lubricant capable of eliminating surface melt fracture such as stearates for the polyolefin processing and polyethylenes for the processing of fluoropolymers.

Modeling concrete fracturing using a hybrid finite-discrete element method

  • Elmo, Davide;Mitelman, Amichai
    • Computers and Concrete
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    • v.27 no.4
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    • pp.297-304
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    • 2021
  • The hybrid Finite-Discrete Element (FDEM) approach combines aspects of both finite elements and discrete elements with fracture mechanics principles, and therefore it is well suited for realistic simulation of quasi-brittle materials. Notwithstanding, in the literature its application for the analysis of concrete is rather limited. In this paper, the proprietary FDEM code ELFEN is used to model concrete specimens under uniaxial compression and indirect tension (Brazilian tests) of different sizes. The results show that phenomena such as size effect and influence of strain-rate are captured using this modeling technique. In addition, a preliminary model of a slab subjected to dynamic shear punching due to progressive collapse is presented. The resulting fracturing pattern of the impacted slab is similar to observations from actual collapse.

Improved nonlinear modelling approach of simply supported PC slab under free blast load using RHT model

  • Rashad, Mohamed;Yang, T.Y.
    • Computers and Concrete
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    • v.23 no.2
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    • pp.121-131
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    • 2019
  • Due to the heterogeneity nature of the concrete, it is difficult to simulate the hyperdynamic behaviour and crack trajectory of concrete material when subjected to explosion loads. In this paper, a 3D nonlinear numerical study was conducted to simulate the hyperdynamic behaviour of concrete under various loading conditions using Riedel-Hiermaier-Thoma (RHT) model. Detailed calibration was conducted to identify the optimal parameters for the RHT model on the material level. For the component level, the calibrated RHT parameters were used to simulate the failure behaviour of plain concrete (PC) slab under free air blast load. The response was compared with an available experimental result. The results show the proposed numerical model can accurately simulate the crack trajectory and the failure mode of the PC slab under free air blast load.

Correlations among Morphological Characteristics of Panax quinquefolium Plants Grown .in British Columbia, Canada (Canada산 인삼의 형태 특성)

  • Smyth, S.R.;Bailey, W.G.;Skretkowiez, A.L.
    • Journal of Ginseng Research
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    • v.12 no.2
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    • pp.145-152
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    • 1988
  • Correlations between various morphological characteristics of Panax quinquefolium plants grown in Lytton, British Columbia, Canada were assessed for 1-through 4-year old plants. Root dry weight, the dependent variable, was found to be strongly related to leaf dry weight, leaf length and root length for 1-and 2-year old plants during the middle of the growing season. For 1- and 2-year old plants at the end of the growing season, root dry weight was found to be related to leaf dry weight, leaf length and stem dry weight. For 3 and 4-year old plants, root dry weight was found to be related to leaf dry weight, leaf length and stem dry weight. For 3- and 4-year old plants, root dry weight was found to be related to leaf dry weight. For practical considerations, this latter relationship provides a simple method for selecting superior plants from which seed can be harvested.

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Ginsenoside Content of North American Ginseng (Panax quinquefolius L. Araliaceae) in Relation to Plant Development and Growing Locations

  • Jackson, Chung Ja C.;Dini, Jean-Paul;Lavandier, Clara;Faulkner, Harold;Rupasinghe, H.P. vasantha;Proctor, John T.A.
    • Journal of Ginseng Research
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    • v.27 no.3
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    • pp.135-140
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    • 2003
  • North American ginseng (Panax quinquefolius L.) was analysed for total ginsenosides and ten major ginsenosides (R$_{0}$ , Rb$_1$, Rb$_2$, Rc, Rd, Re, Rf, Rg$_1$, pseudoginsenoside F$_{11}$ and gypenoside XVII), and variations in ginsenoside content with age of plant (over a four-year-period) and geographic location (Ontario versus British Columbia) were investigated. In the roots the total ginsenoside content increased with age up to 58-100 mgㆍg$^{-1}$ dry weights in the fourth year, but in leaves it remained constant over time. Roots and leaves, moreover, had different proportions of individual ginsenosides. The most abundant ginsenosides were Rb$_1$ (56mgㆍg$^{-1}$ for Ontario; 37mgㆍg$^{-1}$ for British Columbia) and Re (21mgㆍg$^{-1}$ for Ontario; 15 mgㆍg$^{-1}$ for British Columbia) in roots, and Rd (28-38 mgㆍg$^{-1}$ ), Re (20-25 mgㆍg$^{-1}$ ), and Rb$_2$ (13-19 mgㆍg$^{-1}$ ) in leaves. Measurable quantities of Rf were found in leaves (0.4-1.8 mgㆍg$^{-1}$ ) but not in roots or stems. Our results show that ginsenoside profiles in general, and Rf in particular, could be used for chemical fingerprinting to distinguish the different parts of the ginseng plant, and that ginseng leaves could be valuable sources of the ginsenosides Rd, Re, and Rb$_2$.