Mesoporous tantalum oxide catalysts for nitrogen fixation.

A variety of mesoporous tantalum oxide supported catalytic systems were synthesized and investigated for their activities in nitrogen activation, including the Schrauzer-type photocatalytic process and the Haber-Bosch type thermocatalytic process. Mesoporous Ta oxide possesses a high thermal stability, high surface area, tunable wall composition and, most interestingly, variable oxidation states of the transitional metal sites. For this reason it represents a unique support for heterogeneous catalysis. Modification of the surface properties by doping active metal agents and various thermal treatments can further improve the activity. Results obtained in this work showed that for the photocatalytic process pure Ta oxide, with suitable band gap near-UV, exhibited relatively low activity; however, 1 wt% Fe3+ doping increased the activity by a factor of 3. For the Haber process, the Ba-Ru-Ta material was the most active system. Ru3(CO)12 proved to be the best precursor for the active Ru metal component, and Ba(NO 3)2 was the best precursor for the BaO promoter. Remarkably, this system shows a very low activation energy of 9.3 kJ/mol as well as a clear involvement of Ta specie(s) during the catalytic reaction. This suggests a different mechanism than that proposed for standard Ru-based Haber synthesis, which uses alumina, silica and magnesia supports, might be functioning. The results in this thesis clearly show the enormous potential of mesoporous transition metal oxides in catalysis, the first porous support materials offering variable oxidation states. All materials in this work were characterized by a combination of techniques including XRD, TEM, nitrogen adsorption, XPS, EDS, and H 2-TDA. Source: Masters Abstracts International, Volume: 44-03, page: 1373. Thesis (M.Sc.)--University of Windsor (Canada), 2005

Effect of drinking water ozone treatment on select pharmaceuticals and personal care products (PPCPs) and endocrine disrupting compounds (EDCs)

The effect of five process variables on the transformation of 16 selected PPCP/EDCs during drinking water ozonation was systematically studied through 25-1 fractional factorial designed experiments. Dissolved Organic Carbon (DOC) content, ozone dose, and their interaction were most significant for all 16 compounds, and accounted for 60-98 of the observed variability in the transformation efficiencies. Temperature was a significant factor for most of the fast-reacting compounds (kO3 \u3e10 4 M-1s-1), accounting for up to 20 of the change in transformation efficiency, but was not significant for the slow-reacting compounds (kO3 -1s-1). Ozone exposure of \u3e 1.0 mg L\u27-1\u27 min-1 resulted in \u3e 80 transformation of all the 16 compounds at both low (5 C) and high (23 C) temperatures. However, this transformation is expected to be strongly dependent on the nature of the DOC for the slow-reacting compounds

Exploratory Factor Analysis for Validating Traditional Chinese Syndrome Patterns of Chronic Atrophic Gastritis

Background. Traditional Chinese medicine (TCM) has long been used to treat chronic atrophic gastritis (CAG). The aim of the present study was to evaluate the TCM syndrome characteristics of CAG and its core pathogenesis so as to promote optimization of treatment strategies. Methods. This study was based on a participant survey conducted in 4 hospitals in China. Patients diagnosed with CAG were recruited by simple random sampling. Exploratory factor analysis (EFA) was conducted on syndrome extraction. Results. Common factors extracted were assigned to six syndrome patterns: qi deficiency, qi stagnation, blood stasis, phlegm turbidity, heat, and yang deficiency. Distribution frequency of all syndrome patterns showed that qi deficiency, qi stagnation, blood stasis, phlegm turbidity, and heat excess were higher (76.7%–84.2%) compared with yang deficiency (42.5%). Distribution of main syndrome patterns showed that frequencies of qi deficiency, qi stagnation, phlegm turbidity, heat, and yang deficiency were higher (15.8%–20.8%) compared with blood stasis (8.3%). Conclusions. The core pathogenesis of CAG is combination of qi deficiency, qi stagnation, blood stasis, phlegm turbidity, heat, and yang deficiency. Therefore, treatment strategy of herbal prescriptions for CAG should include herbs that regulate qi, activate blood, resolve turbidity, clear heat, remove toxin, and warm yang

Transcription Factors Mat2 and Znf2 Operate Cellular Circuits Orchestrating Opposite- and Same-Sex Mating in Cryptococcus neoformans

Cryptococcus neoformans is a human fungal pathogen that undergoes a dimorphic transition from a unicellular yeast to multicellular hyphae during opposite sex (mating) and unisexual reproduction (same-sex mating). Opposite- and same-sex mating are induced by similar environmental conditions and involve many shared components, including the conserved pheromone sensing Cpk1 MAPK signal transduction cascade that governs the dimorphic switch in C. neoformans. However, the homeodomain cell identity proteins Sxi1α/Sxi2a encoded by the mating type locus that are essential for completion of sexual reproduction following cell–cell fusion during opposite-sex mating are dispensable for same-sex mating. Therefore, identification of downstream targets of the Cpk1 MAPK pathway holds the key to understanding molecular mechanisms governing the two distinct developmental fates. Thus far, homology-based approaches failed to identify downstream transcription factors which may therefore be species-specific. Here, we applied insertional mutagenesis via Agrobacterium-mediated transformation and transcription analysis using whole genome microarrays to identify factors involved in C. neoformans differentiation. Two transcription factors, Mat2 and Znf2, were identified as key regulators of hyphal growth during same- and opposite-sex mating. Mat2 is an HMG domain factor, and Znf2 is a zinc finger protein; neither is encoded by the mating type locus. Genetic, phenotypic, and transcriptional analyses of Mat2 and Znf2 provide evidence that Mat2 is a downstream transcription factor of the Cpk1 MAPK pathway whereas Znf2 functions as a more terminal hyphal morphogenesis determinant. Although the components of the MAPK pathway including Mat2 are not required for virulence in animal models, Znf2, as a hyphal morphology determinant, is a negative regulator of virulence. Further characterization of these elements and their target circuits will reveal genes controlling biological processes central to fungal development and virulence

Phosphorus recovery from a membrane enhanced biological phosphorus removal (MEBPR) process

Phosphorus is an essential yet limited element for sustaining life of human beings. Municipal wastewater contains rich phosphorus, which is not sufficiently recovered or recycled. This dissertation developed a system that could recover phosphorus from wastewater as struvite fertilizer (MgNH₄PO₄•6H₂O). Such a system included three major components — a membrane enhanced biological phosphorus removal (MEBPR) process, a side-stream unit to extract PO₄³⁻ and NH₄⁺ from wasted solids, and a struvite crystallizer. This dissertation focused on optimizing the first two steps through pilot- and bench-scale studies, respectively. The MEBPR process was tested at increasing solids retention time (SRT) to increase total phosphorus (TP) concentration in mixed liquor (ML). The operation at SRT = 60 days proved to be technically feasible and achieved comparable phosphorus removal (95−96 %) and organic carbon removal (91−92 %) to that observed during operation at the control SRT (25 days). The 60-day SRT operation also removed 14 % more nitrogen, wasted 17 % less dry solids, more than doubled the TP concentration of aerobic zone ML, but did not increase membrane fouling rates. Cost analyses showed that the energy requirements were 0.94 and 2.1 kWh/m³ of permeate for SRT = 25 and 60 days, both within the reported range for full-scale membrane bioreactors. To solve foaming problem in the MEBPR process, foam was characterized as an alternative resource for phosphorus recovery. Methods were assessed to extract phosphorus from ML and foam. With suitable conditions, microwave-based hydrogen peroxide advanced oxidation process (MW-H₂O₂ AOP) could extract > 90 % of TP as PO₄-P from foam, and anaerobic P-release could extract up to 60 % from ML. Anaerobic digestion could extract 44−46 % of TP under digestion pHs, 64−65 % with pH ≤ 5.5, and generate sufficient NH₄⁺ that matched the quantities of PO₄³⁻ extracted. Finally, a system was proposed that included an MEBRP process operating at SRT = 60 days, and an anaerobic digester to extract both PO₄³⁻ and NH₄⁺. This system could recover about 60 % of the incoming phosphorus in the influent. To recover more phosphorus, MW-H₂O₂ AOP could be used after anaerobic digestion, whenever justified.Applied Science, Faculty ofCivil Engineering, Department ofGraduat

Few shot object detection for headdresses and seats in Thangka Yidam based on ResNet and deformable convolution

Aiming at the problems of few detecting samples, deformable target sizes and overlapping among targets in the detection of headdresses and seats of Thangka Yidam, we propose an optimised few shot Thangka detection method based on the ResNet and deformable convolution. Firstly, the optimised deep residual network is designed to address the problem of few categories and complicated composition in Thangka images. Then, we replace the 3×3 convolution of the optimised deep residual network with deformable convolution. By introducing the offset of deformable convolution, the receptive field can adapt to the different sizes and shapes of the detection target of Thangka Yidam. Finally, the box regression is achieved through the multi-relation detector, where DT-NMS is proposed to reduce the missed and repeated detection target. Experimental results show that the proposed method has better performance than the SOTA on the COCO dataset. In addition, the AP of 2-way 5-shot on the Thangka dataset is 33.3%, and the AP50 reaches 71.2%, which increases by 4.7% and 5.3%, respectively

Pine caterpillar occurrence modeling using satellite spring phenology and meteorological variables

Outbreaks of leaf-feeding Lepidopteran insects substantially weaken the quality of forest trees and strongly affect the ecosystem functions of plant photosynthesis and carbon uptake. The narrow phenological time window of leaf out about ten days, during which Lepidopteran larvae feed on high nutrient newly flushed leaves, may change the insect community and outbreak dynamics by determining the survival rate of larvae. The Chinese pine Caterpillar ( Dendrolimus tabulaeformis Tsai et Liu ) infestation of the northern Chinese pine ( Pinus tabulaeformis ) forest in China is a major concern, and accurately modeling the day of insect occurrence (DIO) in the spring remains challenging. With continuous in-situ observed insect activities of 20 plots and satellite and meteorological observations from 1983 to 2014, we found a strong synchronization ( r = 0.54, p = 0.001) between the satellite-based vegetation spring phenology, i.e. the green-up day (GUD), and DIO of the pine caterpillar over time. We used partial least squares regression and ridge regression models, and identified that monthly preseason air temperature, wind speed, specific humidity, and downward radiation were key environmental cues that awakened the overwintering pine caterpillars. After removing the collinearity of multiple variables, we showed that the dimensionality reduction-based regression models substantially improved the accuracy of DIO modeling than commonly used models, such as interval and degree-day models. In particular, including GUD significantly enhanced the predictive strength of the models increasing the coefficient of determination ( R ^2 ) by 17.1% and consequently a decrease of 16.5% in the root mean square error. We further showed that evapotranspiration changed the environmental moisture content, which indirectly affected the activities of insects. Our results revealed a useful linkage between spring leaf development and insect occurrence, and therefore are of great importance for the large-scale monitoring of pest outbreaks with future remote sensing observations