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Tracking deforestation, drought, and fire occurrence in Kutai National Park, Indonesia
No full textThe dry lowland and mangrove forests of Kutai National Park (KNP) in Indonesia provide invaluable ecosystem services to local human populations (>200,000 in number), serve as immense carbon sinks to recapture anthropogenic emissions, and safeguard habitats for thousands of wildlife species including the critically endangered Northeast Bornean orangutan (Pongo pygmaeus morio). With recent reports of ongoing illegal logging and large-scale wildfires within this National Park, we sought to leverage the extensive catalogue and processing power of Google Earth Engine to track the rates and influences of forest loss within KNP over various time periods since 1997. We present estimates of forest loss from the Hansen Global Forest Change v1.9 dataset (2000–2021) which detected a loss of 15% (272 km2) of forest cover within KNP since 2000, half of which (137 km2) coincided with the El Niño-induced wildfires of 2015–2016. Using the MCD64A1 C6.1 MODIS dataset, we found significant spatial overlap between burned area and forest loss detections during the 2015–2016 period but identified considerable omissions in the burned area dataset over smallholder farms within KNP. We discuss the implications of deforestation in areas of primary orangutan habitat and how patterns of forest loss have influenced drought and fire dynamics within KNP. Finally, we compare time-series estimates of precipitation, the ENSO index, burned area, and forest loss to demonstrate that fire risk within KNP depends largely—but not exclusively—on drought severity, and that rates of non-fire (gradual) and fire-related (extreme) forest loss threaten the remaining forests of this National Park.Natural Science and Engineering Research Council of CanadaNew Frontiers in Research Fun
Evaluation of the temperature downscaling performance of PRECIS to the BCC-CSM2-MR model over China
No full textIn recent years, the Providing REgional Climates for Impacts Studies (PRECIS) developed by the UK Met Office Hadley Centre has been used widely for climate downscaling and has demonstrated superior performance in reproducing the historical climatology in many regions around the world. However, all previous studies based upon PRECIS were solely driven by the GCMs from the Hadley Centre (i.e., HadCM3 and HadGEM2-ES). This inevitably limits its capability of exploring the uncertainties of regional climate projections caused by different boundary conditions from many other GCMs developed by different research centers around the world. Therefore, in this study, we attempt to investigate the downscaling performance of PRECIS to other GCMs for the first time. In particular, we use the CMIP6 boundary conditions from the BCC-CSM2-MR model from Beijing Climate Center to drive the PRECIS model in order to generate 25 km high-resolution climate scenarios for China. The downscaled temperature simulations from PRECIS for the baseline period (i.e., 1979–2004) are compared to the observational data (CN05.1) to help evaluate the downscaling performance. The results show that PRECIS can provide an obvious improvement in simulating the annual mean temperature over China, particularly in the east of China, with the bias of ~ 1 °C. Future changes in mean temperature over China under the SSP245 and SSP585 emission scenarios are further investigated with PRECIS. The downscaled projections by PRECIS show a smaller increase in temperature compared to its driving BCC-CSM2-MR, except for the late of this century under the SSP585. This study is the first attempt to use PRECIS to downscale a non-Hadley-Centre GCM and the evaluation results suggest that PRECIS does present a superior downscaling performance. The results from this study will provide a scientific basis for using PRECIS to downscale other GCMs in support of the exploration of regional climate projection uncertainties associated with different boundary conditions.Beijing Nova Program of Science and Technolog
Nickel upgrades nitrogen waste
No full textConversion of greenhouse gases and other pollutants to fine chemicals is a global challenge. First-row-transition-metal catalysts show promise as cost-effective tools to combat environmental impacts by managing the carbon and nitrogen cycle. Nitrogen oxyanions are experiencing renewed interest for their use as N1 feedstocks
Three-phase-lag bio-heat transfer model of cardiac ablation
No full textSignificant research efforts have been devoted in the past decades to accurately modelling the complex heat transfer phenomena within biological tissues. These modeling efforts and analysis have assisted in a better understanding of the intricacies of associated biological phenomena and factors that affect the treatment outcomes of hyperthermic therapeutic procedures. In this contribution, we report a three-dimensional non-Fourier bio-heat transfer model of cardiac ablation that accounts for the three-phase-lags (TPL) in the heat propagation, viz., lags due to heat flux, temperature gradient, and thermal displacement gradient. Finite element-based COMSOL Multiphysics software has been utilized to predict the temperature distributions and ablation volumes. A comparative analysis has been conducted to report the variation in the treatment outcomes of cardiac ablation considering different bio-heat transfer models. The effect of variations in the magnitude of different phase lags has been systematically investigated. The fidelity and integrity of the developed model have been evaluated by comparing the results of the developed model with the analytical results of the recent studies available in the literature. This study demonstrates the importance of considering non-Fourier lags within biological tissue for predicting more accurately the characteristics important for the efficient application of thermal therapies.Natural Sciences and Engineering Research Council (NSERC) of CanadaCanada Research Chairs (CRC) Progra
Valorization of the spent catalyst from flue gas denitrogenation by improving bio-oil production from hydrothermal liquefaction of pinewood sawdust
No full textNormally, the spent catalyst (V2O5-WO3/TiO2, denoted as VWTi) is dumped as a solid waste after denitrogenation of flue gas through selective catalyst reduction (SCR). However, this used catalyst contains an abundant amount of acid sites and thus can be potentially utilized as the catalyst in hydrothermal liquefaction (HTL) to produce bio-oil. Thus, in this study, the influences of operational variables on the main HTL products distribution and physicochemical properties of bio-oil were evaluated at 240–320 °C for 0–60 min and 0–20 wt% of catalyst dosage. The results demonstrated that the spent VWTi catalyst significantly promoted the production of bio-oil, yielding the highest bio-oil yield (33.9 wt%) at 300 °C for 30 min with a 10 wt% of catalyst loading. The bio-oil obtained with catalyst under the optimal conditions has a HHV of 28.69 MJ/kg, along with an energy recovery of 51.93%. In addition, the use of the spent VWTi catalyst in the HTL could obtain a higher fraction of phenolics compounds with lower boiling point and lower molecular weight, as identified by TGA and GPC analysis. Overall, this study provides an alternative route to valorize the spent catalyst from flue gas denitrogenation by applying as a catalyst to produce high quality bio-oil production in the biomass HTL process.China Scholarship Counci
Applications of 3‐dimensional printing in small‐animal surgery: A review of current practices
No full textDevelopment of a mist-based printhead for droplet-based bioprinting of ionically crosslinking hydrogel bioinks
No full textIn this paper, a novel droplet-based printhead is developed for 3D bioprinting of ionically crosslinking hydrogel bioinks. Contrary to previous approaches to droplet-based bioprinting, many of which use a liquid crosslinking agent to construct scaffolds, the developed system delivers the crosslinker in mist form within the printhead. A mechanism is developed to remove excess mist within the printhead, which prevents scaffold instability caused by the accumulation of liquid on the printing stage. The developed printhead is compatible with commercial systems and offers good droplet gelation and co-droplet adhesion. It is shown that the gelation rate can be controlled by adjusting the delivery rate of the mist. As a result, it is shown that the delivery rate of the mist has an impact on the shape fidelity and mechanical properties of the printed constructs. The printability and swelling properties of printed constructs crosslinked using different mist delivery rates are studied. Moreover, the impacts of printing parameters including printhead height, mist outlet pressure and printhead channel dimensions on the mist distribution and therefore the gelation rate within the printhead is investigated. Additionally, using high-speed imaging, the effects of mist concentration and droplet velocity on the dynamics of droplet impact onto the surface is characterized. Finally, it is shown that the printed constructs using the developed printhead show a low level of cytotoxicity and high level of cell viability. This development advances the applicability of droplet-based bioprinting to construct complex and biocompatible scaffolds for tissue and organ regeneration.NSERC Discovery GrantCanada Foundation for Innovation GrantNSERC I2I Gran
Factors influencing the accuracy of Canada’s large-scale assessment data: Policies and practices of exclusion, absenteeism, and social promotion
No full textThe purpose of this study was to examine patterns and factors influencing exclusion rates and achievement on large-scale assessments in Canada. Data analysis employed a case study to examine policies and practices of exclusion, absenteeism, and social promotion related to large-scale assessments at the international, national, and provincial levels. In addition, information was solicited from assessment experts regarding exclusion rate practices. Findings revealed significant increases in student performance, which paralleled significant increases in exclusion rates. At the provincial level, the analysis led to the discovery of the relationship between social promotion policies and a document guiding assessment practices in Canada (i.e., Principles of Fair Assessment Practices). This relationship was the rationale given for excluding poor performing students, not learning or physically disabled students, from participating in large-scale assessments. Recommendations include an alignment of exclusion policies between the three levels of administration, documenting students who are unable to participate on large-scale assessment because they are operating too far below grade level as a result of being social promoted, and to over sample provinces and schools with high absenteeism on assessment days