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No description available.

<p>In this study new value-added products were developed from four commercially available refined waxes for use as commercial emulsifiers via the technique of maleation. This research was performed in collaboration with an industrial partner with the hope of developing a wax emulsifier product that could replace commercially used wax emulsifiers in engineered wood product emulsions at a cost reduction by beginning with the design of a cost effective process that could be incorporated into an existing factory production line. Through the investigation and subsequent optimization of this process, a highly maleated product was achieved using 6 different quick and simple approaches. A standardized experimental design was applied to the parameters of the experiment: reaction time, peroxide, starting wax, maleic anhydride concentration, and temperature to observe and understand the individual effects of each on the resultant final product. Three organic peroxide initiators were evaluated; di-<em>tert</em>-butyl peroxide, di-<em>tert</em>-butyl peroxybenzoate and benzoyl peroxide, as well as a thermally initiated approach. The resultant waxes were then identified by their acid number and drop melt point; and from this, the overall efficiency of the combined parameter levels was calculated as a function the initial maleic anhydride amount versus that of the final. The maleated wax emulsifiers were incorporated into emulsions and applied to engineered wood products. Emulsifiers made via the thermally initiated approach showed statistically significant improvements in the desired properties, water absorbance and thickness swell, of the engineered wood products as compared to a commercial control formulation.</p> / Master of Science (MSc)

<p>Developing countries typically suffer far greater than developed countries as a result of earthquakes. Poor socioeconomic conditions often lead to poorly constructed homes that are vulnerable to damage during earthquakes. Literature review in this study highlights the lack of existing fragility curves for buildings in developing countries. Furthermore, fragility curves derived using empirical data are almost nonexistent due to the scarcity of post-earthquake damage data and insufficient ground motion recordings in developing countries. Therefore, this research proposes a methodology for developing empirical fragility curves using ground motion data in the form of USGS ShakeMaps.</p> <p>The methodology has been applied to a case study consisting of damage data collected in Bantul Regency, Indonesia in the aftermath of the May 2006 Yogyakarta earthquake in Indonesia. Fragility curves for non-engineered single-storey unreinforced masonry (URM) homes have been derived using the damage dataset for three ground motion parameters; peak ground acceleration (PGA), peak ground velocity (PGV), and pseudo-spectral acceleration (PSA). The fragility curves indicate the high seismic vulnerability of non-engineered URM homes in developing countries. There is a probability of 80% that a seismic event with a PGA of only 0.1g will induce significant cracking of the walls and reduction in the load carrying capacity of a URM home, resulting in moderate damage or collapse. Fragility curves as a function of PGA and PSA were found to reasonably represent the damage data; however, fits for several PGV fragility curves could not be obtained. The case study illustrated the extension of ShakeMaps to fragility curves, and the derived fragility curves supplement to the limited collection of empirical fragility curves for developing countries. Finally, a comparison with an existing fragility study highlights the significant influence of the derivation method used on the fragility curves. The diversity in construction techniques and material quality in developing countries, particularly for non-engineered cannot be sufficiently represented through simplified or idealized analytical models. Therefore, the empirical method is considered to be the most suitable method for deriving fragility curves for structures in developing countries.</p> / Master of Applied Science (MASc)

yes / In order to study the mechanical behaviors of engineered cementitious composites (ECC) reinforced with various types of polyvinyl alcohol (PVA) fibers and different fiber volume fractions after the freeze-thaw cycles, the rapid freeze-thaw method was used to test the mass loss ratios, longitudinal relative dynamic elastic modulus, compressive strength and flexural strength. The results showed that specimens incurred more serious damage with the increasing of freeze-thaw cycles; however their performance would be improved by fiber type and dosage. Mass loss rate of JPA (specimen with 2% volume content of JP fiber) was lower than JPB (specimen with 1% volume content of JP fiber). Furthermore, the mass loss rate of JPB was lower than that of CPB (specimen with 1% volume content of CP fiber). The longitudinal relative dynamic elastic modulus of JPA was higher than that of JPB while the longitudinal relative dynamic elastic modulus of JPB was higher than that of CPB. In addition, the compressive strength and flexural strength decreased with the increasing of freeze-thaw cycles. Mechanical behaviors of specimens with fiber exhibited better strength than specimens without fiber. Based on the SL 211-2006 code for the design of hydraulic structures against ice and freezing action, JPA and JPB specimens are adequate for use in severe cold regions, while specimen CPA and CPB can be used in cold regions, specimen JPC only can be used in warm regions.

The purpose of this dissertation was to broadly investigate the fate of antibiotic resistance genes (ARGs) and engineered nanomaterials (ENMs) as representative contaminants of emerging concern in wastewater treatment plants (WWTPs). WWTPs may have their performance impacted by ENMs and may also serve as a reservoir and point of release for both ENMs and ARGs into the environment. Of interest were potential adverse effects of ENMs, such as stimulation of antibiotic resistance in the WWTP, toxicity to microbial communities critical for WWTP performance, and toxicity to humans who may be exposed to effluents or aerosols containing ENMs and their transformation products. Response of nine representative ARGs encoding resistance to sulfonamide, erythromycin and tetracycline to various lab-scale sludge digestion processes were examined, and factors that drove the response of ARGs were discussed. Mesophilic anaerobic digestion significantly reduced sulI, sulII, tet(C), tet(G), and tet(X) with longer solids retention time (SRT) exhibiting a greater extent of removal. Thermophilic anaerobic digesters performed similarly to each other and provided more effective reduction of erm(B), erm(F), tet(O), and tet(W) compared to mesophilic digestion. Thermal hydrolysis pretreatment drastically reduced all ARGs, but they generally rebounded during subsequent anaerobic and aerobic digestion treatments. Bacterial community composition of the sludge digestion process, as controlled by the physical operating characteristics, was indicated to drive the distribution of ARGs present in the produced biosolids, more so than the influent ARG composition. Effects of silver (nanoAg), zero-valent iron (NZVI), titanium dioxide (nanoTiO2) and cerium dioxide (nanoCeO2) nanomaterials on nitrification function and microbial communities were examined in duplicate lab-scale nitrifying sequencing batch reactors (SBRs), relative to control SBRs received no materials or ionic/bulk analogs. Nitrification function was only inhibited by high load of 20 mg/L Ag+, but not by other nanomaterials or analogs. However, decrease of nitrifier gene abundances and distinct microbial communities were observed in SBRs receiving nanoAg, Ag+, nanoCeO2, and bulkCeO2. There was no apparent effect of nanoTiO2 or NZVI on nitrification, nitrifier gene abundances, or microbial community structure. A large portion of nanoAg remained dispersed in activated sludge and formed Ag-S complexes, while NZVI, nanoTiO2 and nanoCeO2 were mostly aggregated and chemically unmodified. Thus, the nanomaterials appeared to be generally stable in the activated sludge, which may limit their effect on nitrification function or microbial community structure. Considering an aerosol exposure scenario, cytotoxicity and genotoxicity of aqueous effluent and biosolids from SBRs dosed with nanoAg, NZVI, nanoTiO2 and nanoCeO2 to A549 human lung epithelial cells were examined, and the effects were compared relative to outputs from SBRs dosed with ionic/bulk analogs and undosed SBRs, as well as pristine ENMs. Although the pristine nanomaterials showed varying extents of cytotoxicity to A549 cells, and gentoxicity was observed for nanoAg, no significant cytotoxic or genotoxic effects of the SBR effluents or biosolids containing nanomaterials were observed. Studies presented in this dissertation provided new insights in the fate of ARGs in various sludge digestion processes and ENMs in nitrifying activated sludge system in lab-scale reactors. The study also yielded toxicity data of ENMs to biological wastewater treatment microbial communities and human lung cells indicated by a variety of toxicity markers. The results will aid in identifying appropriate management technologies for sludge containing ARGs and will inform microbial and human toxicity assessments of ENMs entering WWTPs. / Ph. D.

No / The objective of this study was to evaluate the effect of corrosion level on shear behavior of engineered cementitious composite (ECC) beams. Reinforced normal concrete (R-NC) specimens with compressive strength equal to the ECC specimens were also used for control purposes. Ten reinforced concrete beams (five ECC and five NC) with dimensions of 150 x 220 x 1400 mm (5.91 x 8.66 x 55.12 in.) were manufactured for the study. Using accelerated corrosion through the application of a constant current of 1 ampere, four levels of corrosion were established at 5%, 10%, 15%, and 20% of mass loss of the reinforcing bars. To ensure the highest probability of shear failure mode, all beams were tested under a four-point loading system with a shear span-effective depth ratio of 2.5. General structural behavior, strength, stiffness, failure mode, and energy absorption capacities of ECC and R-NC beams subjected to different corrosion levels were evaluated and compared. Experimental results showed a high correlation between calculated mass loss and measured mass loss in reinforcing bars due to accelerated corrosion. Compared to NC, ECC beams exhibited significantly higher strength, stiffness, and energy absorption capacity, along with superior performance in terms of the restriction of damage caused due to corrosion. The increase in corrosion level negatively influenced the structural behavior of the ECC beams tested.

Yes / There is a need for an inexpensive, reliable and fast monitoring tool to detect contaminants in a short time, for quick mitigation of pollution sources and site remediation, and for characterization of natural dissolved organic matter (DOM). Fluorescence spectroscopy has proven to be an excellent technique in quantifying aquatic DOM, from autochthonous, allochthonous or anthropogenic sources. This paper reviews the advances in in situ fluorescence measurements of DOM and pollutants in various water environments. Studies have demonstrated, using high temporal-frequency DOM fluorescence data, that marine autochthonous production of DOM is highly complex and that the allochthonous input of DOM from freshwater to marine water can be predicted. Furthermore, river measurement studies found a delayed fluorescence response of DOM following precipitation compared to turbidity and discharge, with various lags, depending on season, site and input of dissolved organic carbon (DOC) concentration. In addition, research has shown that blue light fluorescence (λemission = 430–500 nm) can be a good proxy for DOC, in environments with terrestrial inputs, and ultraviolet fluorescence (λemission = UVA–320–400 nm) for biochemical oxygen demand, and also E. coli in environments with sanitation issues. The correction of raw fluorescence data improves the relationship between fluorescence intensity and these parameters. This review also presents the specific steps and parameters that must be considered before and during in situ fluorescence measurement session for a harmonized qualitative and quantitative protocol. Finally, the strengths and weaknesses of the research on in situ fluorescence are identified. / Authors, E.M. Carstea and C.L. Popa, acknowledge the support of the Ministry of Research and Innovation, CNCS-UEFISCDI, project number PN-III-P1-1.1-TE-2016-0646, within PNCDI III, project number 18N/2019, under the Core Program OPTRONICA VI, project number 19PFE/17.10.2018 and project number 152/2016, SMIS 108109.