Browsing by Author "Liu, Yang"

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    Convalescent plasma for adults with acute COVID-19 respiratory illness (CONCOR-1): study protocol for an international, multicentre, randomized, open-label trial
    (2021-05-04) Bégin, Philippe; Callum, Jeannie; Heddle, Nancy M; Cook, Richard; Zeller, Michelle P; Tinmouth, Alan; Fergusson, Dean A; Cushing, Melissa M; Glesby, Marshall J; Chassé, Michaël; Devine, Dana V; Robitalle, Nancy; Bazin, Renée; Shehata, Nadine; Finzi, Andrés; McGeer, Allison; Scales, Damon C; Schwartz, Lisa; Turgeon, Alexis F; Zarychanski, Ryan; Daneman, Nick; Carl, Richard; Amorim, Luiz; Gabe, Caroline; Ellis, Martin; Sachais, Bruce S; Loftsgard, Kent C; Jamula, Erin; Carruthers, Julie; Duncan, Joanne; Lucier, Kayla; Li, Na; Liu, Yang; Armali, Chantal; Kron, Amie; Modi, Dimpy; Auclair, Marie-Christine; Cerro, Sabrina; Avram, Meda; Arnold, Donald M
    Abstract Background Convalescent plasma has been used for numerous viral diseases including influenza, severe acute respiratory syndrome, Middle East respiratory syndrome and Ebola virus; however, evidence to support its use is weak. SARS-CoV-2 is a novel coronavirus responsible for the 2019 global pandemic of COVID-19 community acquired pneumonia. We have undertaken a randomized controlled trial to assess the efficacy and safety of COVID-19 convalescent plasma (CCP) in patients with SARS-CoV-2 infection. Methods CONCOR-1 is an open-label, multicentre, randomized trial. Inclusion criteria include the following: patients > 16 years, admitted to hospital with COVID-19 infection, receiving supplemental oxygen for respiratory complications of COVID-19, and availability of blood group compatible CCP. Exclusion criteria are : onset of respiratory symptoms more than 12 days prior to randomization, intubated or imminent plan for intubation, and previous severe reactions to plasma. Consenting patients are randomized 2:1 to receive either approximately 500 mL of CCP or standard of care. CCP is collected from donors who have recovered from COVID-19 and who have detectable anti-SARS-CoV-2 antibodies quantified serologically. The primary outcome is intubation or death at day 30. Secondary outcomes include ventilator-free days, length of stay in intensive care or hospital, transfusion reactions, serious adverse events, and reduction in SARS-CoV-2 viral load. Exploratory analyses include patients who received CCP containing high titre antibodies. A sample size of 1200 patients gives 80% power to detect a 25% relative risk reduction assuming a 30% baseline risk of intubation or death at 30 days (two-sided test; α = 0.05). An interim analysis and sample size re-estimation will be done by an unblinded independent biostatistician after primary outcome data are available for 50% of the target recruitment (n = 600). Discussion This trial will determine whether CCP will reduce intubation or death non-intubated adults with COVID-19. The trial will also provide information on the role of and thresholds for SARS-CoV-2 antibody titres and neutralization assays for donor qualification. Trial registration Clinicaltrials.gov NCT04348656 . Registered on 16 April 2020.
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    Development of Upflow Aerobic Granular Sludge Bioreactor (UAGSBR) for Treatment of High-strength Organic Wastewater
    (2019-04-02) Hamza, Rania Ahmed Sayed Eid; Tay, Joohwa; Hettiaratchi, Joseph Patrick A.; Koshnazar, Rahil; Nassar, Nashaat N.; Liu, Yang
    Industrial wastewater, typically referred to as high-strength wastewater, is a major source of ‎water pollution due to its elevated organic content. High-strength organic wastewaters are ‎characterized by chemical oxygen demand (COD) concentrations greater than 4000 mg/L. ‎The effluents of these industries need to undergo biological treatment to remove the organic ‎matter. However, conventional biological treatment processes fail to stabilize high-strength ‎wastewater to regulatory limits. Aerobic treatment processes are not economically feasible for ‎the treatment of high-strength organic wastewater. Anaerobic processes suffer from low ‎growth rate of the microorganisms, high sensitivity to toxic loadings, fluctuations in ‎environmental conditions, and require post-treatment to bring the water quality within ‎regulations. This work aimed at developing an upflow aerobic granular sludge bioreactor (UAGSBR) to ‎provide a downstream effective treatment process in order to combine the benefit of ‎anaerobic digestion (i.e., biogas production) with the benefit of aerobic treatment (i.e., better ‎removal of organics). Moreover, it is hypothesized that effluent of anaerobic treatment ‎provides a solubilized organic matter suitable for subsequent aerobic treatment because of its ‎reduced organic strength and enhanced amounts of nitrogen and phosphorus. The combined ‎system will overcome the limitations of both anaerobic and aerobic systems, such as long ‎treatment duration and low stability due to rapid bacterial growth, respectively. ‎In this project, biogranulation, formed by the self-immobilization of microorganisms, was ‎employed as a novel technology in an upflow semi-pilot-scale bioreactor. These granules are ‎dense microbial communities packed with different bacterial species, which can achieve rapid ‎treatment for high volumes of wastewater in a smaller footprint when compared to ‎conventional biomass. Mechanisms of granule formation and stability considering influential ‎factors such as system start-up, organic loading rate, food-to-microorganisms ratio, and ‎nutrients addition were examined. Treatment efficiency, assessed in terms of organics and ‎nutrients (nitrogen and phosphorus) removal, was above 90%. The UAGSBR provides a ‎compact system for high-strength organics wastewater treatment (at 20-30% spatial footprint ‎of a conventional plant). ‎ ‎ ‎
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    Experimental and Mechanism Study of Superheated SAGD vs. Conventional SAGD Technique: A Cost-Effective Scheme for Superheated SAGD
    (2022-04-27) Huang, Ke; Huang, Siyuan; Jiang, Qi; Liu, Yang
    Steam-assisted gravity drainage (SAGD) is one of the steam injection techniques to exploit heavy oil and extra heavy oil resources, where the nature of steam is crucial to the production efficiency. Replacing saturated steam with superheated steam can effectively improve the steam quality at the bottom of the well and the production efficiency. In this study, based on the 2-D SAGD experiments, the recovery mechanisms of SAGD under the 220°C saturated steam and 260°C (superheated degree of 40°C) and 300°C (superheated degree of 80°C) superheated steam are compared and analyzed. The numerical model was developed based on experimental results, and the influence of steam superheated degree on the recovery degree of the SAGD process was further investigated. The physical experiment results and numerical simulation results show that the advantages of high enthalpy and large specific volume of superheated steam are significant at the horizontal expansion stage of the steam chamber stage compared to those of saturated steam. However, although the superheated steam can improve the recovery degree, the economic efficiency may decrease with the addition of superheated steam since it requires higher energy to generate the superheated steam. Thus, the SOR (steam-oil ratio) cannot appropriately describe the energy and economic efficiency when superheated steam is considered. Therefore, the cumulative FOR (fuel-oil ratio) is proposed, and the optimal superheated degree, optimal injection strategy, and its relation with the recovery mechanisms are studied. The results indicate that using superheated steam at 80°C superheated degree during the steam chamber horizontal expansion stage can increase the recovery factor around 12% and also reduce the cumulative FOR around 5.3 compared to the conventional SAGD strategy.
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    Exploring Temporal Loss Tolerance of Video Codecs for QoE Enhancement in Adaptive Streaming
    (2021-08-25) Liu, Yang; Wang, Mea; Alim, Usman; Krishnamurthy, Diwakar
    Video streaming is not only for entertainment now, but also for lessons, communications, meetings, and even diagnosis. Quality of Experience (QoE) is the most important concerned aspect by content providers and platform providers. Among all the experience, enduring stalls is the most frustrating one. In this thesis, we present Bandwidth-Efficient Temporal Adaptation (BETA) and Temporal Adaptive Streaming over QUIC (TASQ), whose target is to improve the smoothness of video playbacks even under extreme network conditions. We investigate temporal loss tolerance for HEVC and AV1, and apply the optimization on video streaming. Results show a drastic improvement on the smoothness and the QoE.
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    Improving Quality of Experience (QoE) of Dynamic Adaptive Streaming (DAS) Systems
    (2019-09-19) James, Cyriac; Wang, Mea; Krishnamurthy, Diwakar; Williamson, Carey L.; Alim, Usman R.; Liu, Yang
    Dynamic Adaptive Streaming (DAS) systems dominate today's video streaming over the Internet, and operate by adapting video quality based on network throughput variation using discrete quality levels. Despite their popularity, it lacks an effective adaptation that minimizes stalls and quality switches while maximizing visual quality, especially when available bandwidth varies. The conventional approach to adaptation is to make a decision on the next video segment quality based on prior throughput measurements. This approach is not robust to bandwidth fluctuation at small time scales, which can consequently lead to stalls, bandwidth waste, and unstable quality, mainly due to the inability to mitigate significant bandwidth reduction during the segment download. MultiPath TCP (MPTCP) is an emerging paradigm that could offer significant benefits to video streaming by harnessing bandwidth from multiple network interfaces, in particular on mobile and desktop devices with support for both WiFi and cellular networks. We first investigate this off-the-shelf solution to improve video streaming performance by harvesting additional bandwidth over always or intermittently available secondary link under different bandwidth variability conditions. Our measurement study yields mixed results. While beneficial to user experience when primary link bandwidth is unstable or constrained, MPTCP may not offer any advantage otherwise, and sometimes could be detrimental. We then propose BETA – Bandwidth-Efficient Temporal Adaptation, an agile approach that allows DAS players to refine the quality level within video segments on the fly, according to the actual bandwidth conditions experienced while downloading each segment. We define a new DAS-oriented transmission order of video frames within segments that facilitates decodability of partial frames, and paves the way for changing the paradigm from discrete to continuous bitrate ladders for DAS. BETA can work with any adaptation algorithm that runs on a DAS player to significantly improve robustness and efficiency in dynamic network environments and for low-latency streams, as well as dramatically reduce content storage and encoding infrastructure requirements.
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    Mycoplasma bovis subverts autophagy to promote intracellular replication in bovine mammary epithelial cells cultured in vitro
    (2021-10-14) Liu, Yang; Deng, Zhaoju; Xu, Siyu; Liu, Gang; Lin, Yushan; Khan, Sohrab; Gao, Jian; Qu, Weijie; Kastelic, John P.; Han, Bo
    Abstract Mycoplasma species are the smallest prokaryotes capable of self-replication. To investigate Mycoplasma induced autophagy in mammalian cells, Mycoplasma bovis (M. bovis) and bovine mammary epithelial cells (bMEC) were used in an in vitro infection model. Initially, intracellular M. bovis was enclosed within a membrane-like structure in bMEC, as viewed with transmission electron microscopy. In infected bMEC, increased LC3II was verified by Western blotting, RT-PCR and laser confocal microscopy, confirming autophagy at 1, 3 and 6 h post-infection (hpi), with a peak at 6 hpi. However, the M. bovis-induced autophagy flux was subsequently blocked. P62 degradation in infected bMEC was inhibited at 3, 6, 12 and 24 hpi, based on Western blotting and RT-PCR. Beclin1 expression decreased at 12 and 24 hpi. Furthermore, autophagosome maturation was subverted by M. bovis. Autophagosome acidification was inhibited by M. bovis infection, based on detection of mCherry-GFP-LC3 labeled autophagosomes; the decreases in protein levels of Lamp-2a indicate that the lysosomes were impaired by infection. In contrast, activation of autophagy (with rapamycin or HBSS) overcame the M. bovis-induced blockade in phagosome maturation by increasing delivery of M. bovis to the lysosome, with a concurrent decrease in intracellular M. bovis replication. In conclusion, although M. bovis infection induced autophagy in bMEC, the autophagy flux was subsequently impaired by inhibiting autophagosome maturation. Therefore, we conclude that M. bovis subverted autophagy to promote its intracellular replication in bMEC. These findings are the impetus for future studies to further characterize interactions between M. bovis and mammalian host cells.
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    Phosphorus Recovery from Synthetic Municipal Wastewater through Lignin-induced Struvite Precipitation
    (2020-01-08) Li, Mozhu; Lu, Qingye; Liu, Yang; Hu, Jinguang; Shor, Roman J.
    Phosphorus recovery from wastewaters is essential to resolve the problems of the fast depletion of phosphate rocks due to the increasing demand for phosphorus fertilizer, and eutrophication due to excessive phosphorus discharging from wastewater. In this study, the feasibility of adding alkaline lignin as seed materials to promote phosphorus recovery through fertilizer struvite (NH4MgPO4·6H2O) crystallization from synthetic municipal wastewater was evaluated via batch experiments. Influencing factors tested included lignin dosage, Mg/P molar ratio, and pH. Lignin addition enhanced phosphorus recovery by 44.6% at a relatively low pH of 7.9 with Mg/P molar ratio of 1.5 and lignin dosage of 6 g/L, resulting in the reduced potential of co-precipitation and the cost-saving on alkali addition. As pH increases, however, this effect becomes less noticeable because of the higher solubility of lignin in wastewater. The characterizations by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and zeta potential analysis, combined with precipitation modeling by a thermodynamic model software (Visual MINTEQ) were done to understand the process. Struvite-lignin clusters were identified, likely due to the in-situ-pH-favorable nucleation sites on lignin enhanced struvite crystallization. As for the application in wastewater with different characteristics, the effect of lignin on enhancing phosphorus recovery efficiency is still significant under different PO4-P and NH4-N concentrations, indicating the effect-stability and availability of lignin in promoting struvite crystallization. As for the total suspended solids (TSS), the results show that the effect of TSS on phosphorus recovery efficiency is not significant (p > 0.05). Moreover, lignin is more efficient in increasing phosphorus recovery under relatively lower alkalinity while could reduce the co-precipitates potential under higher alkalinity. Overall, this study provides a new possibility of the use of lignin from paper mill black liquor as seed material to enhance phosphorus recovery from wastewater, making the struvite production more efficient and cost-effective.
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    Re-emergence of canine Leishmania infantum infection in mountain areas of Beijing
    (2023-03-30) Liu, Gang; Wu, Yuanheng; Wang, Lei; Liu, Yang; Huang, Wei; Li, Yifan; Gao, Mengbo; Kastelic, John; Barkema, Herman W.; Xia, Zhaofei; Jin, Yipeng
    Abstract Canine Leishmaniasis (CanL) is an endemic infectious disease in China, causing visceral Leishmaniasis (VL) and resulting in important public health problem. However, in the last 3 y, endemic trends have changed considerably and spatial–temporal aggregation areas have shifted from northwestern to central China. Although Beijing was an endemic area for CanL in the last century, this disease has not been reported in Beijing since control programs were implemented in the 1950s. In the present study, PCR and immunochromatographic (ICT) were used to estimate prevalence of Leishmania infection in domestic dogs living in Beijing, a VL re -emergencearea. In total, 4420 canine blood samples were collected at vet clinics in 14 districts of Beijing. Overall prevalence (percentage of dogs seropositive and/or PCR positive) of CanL infection in Beijing was 1.22% (54/4420). However, prevalence of CanL in the western mountain areas was 4.68% (45/961), significantly higher than that (0.26%, 9/3459) of the plains. In addition, multilocus sequence typing (MLST) of seven enzyme-coding genes was used to examine phylogenetic relationships of CanL strains. Forty-one Leishmania infantum isolates were well separated from the other strains and divided into five major clades (A to E) by MLST analysis. All clades were closely related to strains from Sichuan Province and Gansu Province. A phylogenetic tree, based on the MLST, revealed that L. infantum in Beijing was genetically related to strains from western endemic of Mountain type VL in China. In conclusion, CanL has re-emerged in Beijing, and almost 5% of dogs living in Beijing’s mountain areas were infected with L. infantum. The phylogenetic tree based on MLST effectively distinguished species of Leishmania and reflected geographical origins. Because dogs are considered a natural reservoir, comprehensive control measures including surveillance, phylogenetic analyses and management should be implemented to mitigate or eliminate Leishmaniasis.
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    Removal of acid-extractable organics from oil sands process-affected water using carbon-based adsorbents
    (2017) Bhuiyan, Tazul; Hill, Josephine; Abedi, Jalal; Song, Hua; Achari, Gopal; Liu, Yang
    In surface mining process, 1.9 volumes of freshwater are used for each volume of bitumen produced and the used water, called oil sands process-affected water (OSPW), is stored in tailings ponds. Acid-extractable organics (AEO), one of the components of OSPW, are believed to be the main component of toxicity in OSPW, and create harmful effects to aquatic organisms, mammals and birds. To discharge OSPW into environment safely and reclaim the tailings ponds into natural ecosystem, the objective is to remove 90-99% AEO from OSPW. Canada has abundant resources of biomass waste materials to prepare biochar and activated carbon (AC), which can be applied for the removal of AEO from OSPW. In this thesis, the impact of biochar and AC properties, and synthesis methods for the removal of AEO from OSPW have been studied. Aspen wood AC samples were prepared by chemical (H3PO4) and physical (CO2) activation methods, and characterized and tested for the removal of AEO from steam-assisted gravity drainage (SAGD) water and OSPW. The role of physical properties of AC for AEO removal was investigated. The surface area and total pore volume of AC were positively correlated with AEO removal of SAGD water and OSPW.The impact of biochar properties on AEO adsorption from OSPW was studied. Biochar from wheat straw with the highest ash content (14 %) had the highest adsorption capacity (0.59 mg/g). The adsorption capacity had a positive correlation with metal content (mainly Al and Fe) of biochar. These results indicated that the metal sites acted as Lewis acids that can form coordination bonds with the naphthenates, the main constituent of the AEO. The influence of physical properties of carbon-based adsorbents on AEO adsorption kinetics was also investigated. As expected, there were diffusion limitations when adsorbing AEO onto microporous adsorbents, while larger pore materials were free of intra-particle diffusion limitations, as confirmed by the adsorption of alkylated cyclopentane carboxylic acid. The outcome of this research provides an insight into the application of biomass based adsorbents for AEO adsorption.
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    Traffic Analysis of Two Scientific Web Sites
    (2015-12-15) Liu, Yang; Williamson, Carey; Williamson, Carey; Arlitt, Martin; Donovan, Eric
    This thesis presents a workload characterization study of two scientific Web sites at the University of Calgary based on a four-month period of observation (from January 1, 2015 to April 30, 2015). The Aurora site is a scientific site for auroral researchers, providing auroral images collected from remote cameras deployed in northern Canada. The ISM site is a scientific site providing lecture materials to about 400 undergraduate students in the ASTR 209 course. Three main observations emerge from our workload characterization study. First, scientific Web sites can generate extremely large volumes of Internet traffic, even when the user community is seemingly small. Second, robot traffic and real-world events can have surprisingly large impacts on network traffic. Third, a large fraction of the observed network traffic is highly redundant, and can be reduced significantly with more efficient networking solutions.
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    Understanding the Transition of Teachers from Game Users to Game Designers
    (2018-07-10) Liu, Yang; Lock, Jennifer; Burwell, Catherine; Kim, Beaumie
    Video games play an important role in education, having a strong influence on the Net Generation; however, the idea of teachers as designers of digital classroom games to support student learning has not been widely embraced. The purpose of this study was to gain a deeper understanding of internal and external factors that influence teachers’ capacity to teach and inspire them to move from game users to game designers. This mixed-method case study involved a group of teachers who used and/or designed games for students. The four unique case groups were grounded in three cities and four school districts in Alberta, Canada. Qualitative data were collected from five teachers and six school administrators, six student focus group interviews, eight in-class observations, and two teacher-designed games. Quantitative data were collected from one online survey completed by all five participating teachers. First and second cycle data coding and analyses (Saldaña, 2013) were used to answer the following four research questions: 1) What are the key factors that influence teachers in using digital game-based learning environments? 2) What are the key factors that influence teachers in designing digital game-based learning environments)? 3) What are the conditions needed to develop teachers’ capacity to be designers of digital games? 4) What factors influence the transition of teachers from being game users to game designers to support student learning. iii Key findings from the analysis showed that 1) teachers’ passion towards Digital Gamebased Learning (DGBL) played an important role in motivating them not only to use games but design games, and 2) their technical and pedagogical knowledge worked as a foundation to help teachers transition from game users to game designers. The implications of this study are: 1) my research showcased potential opportunities for both pre-service and in-service teachers regarding designing games in the classroom; 2) school administrators my reference my study to provide resources to support teachers’ innovative teaching approaches and encourage them to be risk-takers; and 3) my research offers options for professional developers to develop courses on game design in order to prepare teachers to use/design games in pedagogically sound ways.