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A reproducible in vitro model of mechanically injured (scalpel cut) articular cartilage was developed in this work utilising bovine and human osteochondral tissue. Using fluorescence-mode confocal laser scanning microscopy (CLSM), the model allowed (1) spatial and temporal quantification of in situ (within the matrix) chondrocyte viability following a full thickness cartilage injury and (2) serial evaluation of three chondroprotective strategies in injured bovine and human articular cartilage: (a) medium osmolarity (b) medium calcium concentration and, (c) subchondral bone attachment to articular cartilage. Medium osmolarity significantly influenced superficial zone chondrocyte death in injured (scalpel cut) bovine and human articular cartilage. Greatest percentage cell death occurred at 0 mOsm (distilled water). Conversely, a raised medium osmolarity (600 mOsm) was chondroprotective. The majority of in situ cell death occurred within 2.5 hours of the experimental injury, with no further increase over 7 days. Exposure of articular cartilage to calcium-free media significantly decreased superficial zone chondrocyte death in injured (scalpel cut) articular cartilage compared with exposure to calcium-rich media (2-20 mM). In calcium-rich media, the extent of percentage cell death increased with increasing medium calcium concentration but remained localised to the superficial zone of injured articular cartilage over 7 days. However, in calcium-free media, there was an increase in percentage cell death within deeper zones of injured articular cartilage over 7 days. Excision of subchondral bone from injured (scalpel cut) articular cartilage resulted in an increase in chondrocyte death at 7 days that occurred in the superficial zone of injured as well as the adjacent uninjured regions of articular cartilage. However, the presence of subchondral bone in the culture medium prevented this increase in chondrocyte death within the superficial zone. Subchondral bone may have interacted with articular cartilage via soluble mediator(s) that influenced chondrocyte survival. In human articular cartilage, healthy subchondral bone also interacted with articular cartilage in explant culture and promoted in situ chondrocyte survival, while sclerotic subchondral bone was detrimental to chondrocyte viability. These findings are of translational relevance to fluid management systems used during open and arthroscopic articular surgery, clinical and experimental research into cartilage injury, repair and degeneration as well as current techniques of tissue engineering.

Many culverts in Ohio are nearing the end of their design lives and have a risk of collapsing. Sliplining, a process where a pipe with a smaller diameter is inserted inside a host pipe and the annular gap between them is filled with grout, is a technique that is frequently utilized for the rehabilitation of culverts. In this study, a number of sliplined culverts in Ohio were subjected to field inspections, during which a hammer-sounding test method and backscatter computed tomography were used. These investigations showed that the annular spaces were not completely filled in. Consequently, the existing standards for grouting material established by the Ohio Department of Transportation (ODOT) require certain revisions. As cellular grouts were not described in depth in the ODOT specifications at the time of this research, the project’s primary objective was to conduct laboratory tests on these materials. The experiment in the laboratory considers various mix proportions in addition to applying various foaming agents to modify the material’s physical properties, including flowability, temperature, stability, and other characteristics. The impact on grout stability was detected when it had an extremely low density and when the cellular grout was exposed to a high temperature.In additional, it was discovered that the grout materials significantly impacted the load-carrying capacity of sliplined corrugated metal pipes. The current research aims to investigate the load-carrying capacity of the culverts sliplined with cellular grout as well as to investigate the effect of voids on the load-carrying capacity of the culverts by studying sliplined culverts with partially filled annular spaces. The findings of this investigation highlighted how critical it is to fill the annulus of sliplined culverts completely. A side-by-side comparison of partially filled annular spaces with voids at different positions revealed that voids in the crown position significantly reduce the load-carrying capacity of the culverts and are more consequential than voids in the springline position. Finally, large batches of cellular grout were tested in the field to confirm their pumpability and were installed in the annular spaces between two corrugated steel pipes in large scale field tests. It was determined that the cellular grout is suitable for the sliplining culverts, since it performed remarkably well when it came to filling annular spaces.

Sliplining is one of the most preferred and common rehabilitation methods for deteriorated culverts in the United States. In this method, a new pipe (liner) having a smaller diameter is inserted into the existing pipe (host pipe), and the annular space between the two pipes is filled with different grouting materials. Controlled Low Strength Material (CLSM) is a commonly used grout material for filling the annulus void. However, DOT inspectors have reported the absence of grout materials in the annular space between the host and liner pipe, which cannot be detected during or immediately after the construction. The key objective of this study was to develop new CLSM mixture proportions for sliplined culverts by improving the properties, such as flowability, bleeding, unconfined compressive strength and other properties. The current research also seeks to explore the load-carrying capacity of sliplined culverts by utilizing the improved grout material. The impact of voids in a partially filled annular space on the load-carrying capacity of a sliplined culvert is also investigated in this research. Several optimum mix designs were developed with improved characteristics compared to the typical CLSM mixtures for sliplining. The contribution of grout materials was found to be very significant in the load-carrying capacity of sliplined corrugated metal pipes. This result specified the importance of complete filling of the annulus of sliplined culverts. Finally, the investigation on partially filled annular voids showed that the void at the crown position significantly reduce the load-carrying capacity of the sliplined culverts, and are more consequential than the voids at the springline position.

Microbiologically influenced corrosion (MIC) has been a popular research topic in the corrosion field due to continuous failures caused by MIC. It has caused billions of dollars in financial losses in the United States alone every year. Biofilms areoften blamed for causing MIC. Sulfate reducing bacteria (SRB) are the principalspecies in publications about MIC research and case studies of MIC failure. Other than SRB, some other species are capable ofinitiating MIC as well. More attention and resources have been focused on MIC research than ever before. Many mechanisms and models have been reported to explain how MIC occurs. The cathodic depolarization theory (CDT) was well-accepted and inspired most of the other theories, although with a few limitations. In 2009, the Biocatalytic Cathodic Sulfate Reduction (BCSR) theory was proposed to describe the process of MIC caused by SRB from an electrogenic perspective.In this research, the starvation test and the electron mediator testwere doneusing a field collected biofilm consortium to study the BCSR theory. Biofilms caused more severecorrosion in the modified ATCC 1249 medium, in which the carbon sources were reduced, than in the full strength ATCC 1249 medium. This supports the BCSR theory that when sessile cells lack a carbon source, they switch the electrondonorsfroma carbonsource to elementaliron. The electron mediator test was done in the modified ATCC 1249 medium, in which all carbon sources were completely removed. Riboflavin was chosen as the electron mediator. The maximum pit depth in the presence of riboflavin was less, however,more weight loss was obtained. It indicated that in the presence of the electron mediator the biofilm wasable to attack the coupon evenly. Therefore, more general corrosion instead of localized corrosion was observed on the coupon surface when riboflavin was added.After the mechanistic studies had beenaddressed, the mitigation of the field collectedbiofilm consortia was investigated. First of all, twoD-amino acids,D-serine and D-threonine, were individuallytested as biocide enhancers of tetrakis hydroxymethyl phosphonium sulfate (THPS)in the mitigation of Desulfovibrio vulgaris biofilms. The results show that they are effective biocide enhancers for THPS. The mechanism of D-amino acids triggering the biofilm dispersal was investigated.Secondly, a novel biocide cocktail of glyceryl trinitrate(GTN) and caprylic acid (CA) was tested. D-methionine enhanced the efficacy of GTN + CA.Finally, D-amino acid mixtures were tested as biocide enhancers of THPS, alkyldimethylbenzylammonium chloride (ADBAC), and tributyl tetradecyl phosphonium chloride(TTPC) in the mitigation of field collectedbiofilm consortia. Individual D-amino acids were not able to enhance the efficacy of biocides since the effect of D-amino acids triggering biofilm disassembly was specific to the types of D-amino acid and the species. Different species require different D-amino acids as signal molecules. Three different D-amino acid mixturesincluding 4, 8, and 12 different D-amino acids were tested. The results show that these three D-amino acid mixtureswere able to enhance the efficacy of THPS, ADBAC, and TTPC in both biofilm prevention and removal tests.

Abstract: The oil sands process-affected water (OSPW) generated from bitumen extraction of oil sands by industries in Northern Alberta, Canada, is a great environmental concern because of the OSPW toxicity in the environment. This toxicity has been attributed to a group of alicyclic and aliphatic compounds containing carboxyl radicals known as naphthenic acids (NAs). Thus, appropriate OSPW treatment approaches are urgently needed to permit the safe discharge of treated OSPW to the receiving environment. By realizing the above need, the current study treats oil sands process-affected water (OSPW) using engineered granular activated carbon (GAC) biofilm reactors by applying different modes of operation (continuous, semicontinuous and batch) for both raw and ozonated OSPW treatments. After 120 days of continuous operation of a GAC fluidized bed biofilm reactor (FBBR), it was shown that the GAC-FBBR process (adsorption and biodegradation) removed more than 86% of classical NAs from raw OSPW. Generally, ozonation is known to be effective in the removal of NAs from raw OSPW. Using a combined 80 mg/L utilized ozone dose followed by GAC-FBBR treatment of ozonated OSPW resulted in the removal of > 99% of classical NAs. In addition, the overall removal of the acid extractable organic-fraction (AEF) and chemical oxygen demand (COD) were 88% and 62%, respectively from this combined process. Further analysis of the microbial community using polymerase chain reaction (PCR) - denatured gradient gel electrophoresis (DGGE) from both raw and ozonated OSPW and their respective GAC-FBBR biofilms showed that there was reduced diversity of the microbial structure in the GAC biofilm with the majority of the bacteria being carbon degraders. Further study investigated the synergistic removal of NAs (classical and oxidized) and toxicity from a simultaneous GAC adsorption and biodegradation treatment of raw and ozonated OSPW (20 mg/L utilized ozone dose). At a GAC dose of 0.4 g GAC/L OSPW, this process removed 93% and 96% of classical NAs, and 74% and 77% of oxidized NAs from raw and ozonated OSPW, respectively. As well, this process reduced the toxicity of both raw and ozonated OSPW. There was higher removal of COD, AEF and NAs from the simultaneous GAC adsorption and biodegradation treatment of OSPW compared to the biodegradation or adsorption only treatments which indicated the enhanced bioregeneration in the GAC biofilm process. The lower utilized ozone dose used in these experiments (as compared with 80 mg/L previously) had little impact on the removal of both classical and oxidized NAs in the raw OSPW as compared to the 80 mg/L utilized ozone dose used in previous experiments. The analysis of the microbial community using PCR-DGGE cannot reveal the comprehensive and complete characterization of microbial community in OSPW. Therefore, a high throughput 454-pyrosequencing was performed for analyzing the microbial community in the GAC biofilm, where biofilm was allowed to form in another set of experiments using a semicontinuous process (batch process with continuous change of OSPW). Frequent observations of the biofilm growth (every six days) on the GAC surface was performed using a confocal laser scanning microscope, real time PCR, and heterotrophic plate count with results showing an effective growth of biofilm. The dominant microbial composition in the GAC biofilm was Proteobacteria and further analysis of Proteobacteria revealed that the GAC biofilm was rich with carbon degrading orders of bacteria namely Myxococcales, Pseudomonadales, and Burkholderiales. The GAC biofilm microbial community was able to remove over 66% of NAs in the ozonated OSPW treatment after a short contact time. Overall the study demonstrated an effective removal of NAs (classical and oxidized) and toxicity from OSPW, which indicated that the GAC biofilm treatment approach is a promising technology for OSPW remediation.