The advent of industrial, fertilizer-intensive agriculture during the 20th century has promoted export of anthropogenic nutrients, spurring degradation of ecosystem biodiversity and water quality. Exported nitrogen and phosphorus are recognized drivers of this deterioration, and require management. In the mid-1990s, denitrifying bioreactors (DNBRs), a subsurface, edge-of-field best management practice (BMP) that intercepts and treats agricultural drainage by supporting nitrate-attenuating denitrification with a saturated, carbon-filled substrate, were developed. Since then, their utility has expanded, and recent studies have unearthed biochar's capability to stimulate simultaneous nitrate (NO3--N) and phosphate (PO43--P) removal in DNBRs. This study investigated biochar's potential as an amendment to the traditional woodchip media by conducting nine, five-day trials on twelve laboratory-scale, horizontal flow-through DNBR columns. Three media types were tested: woodchips (W), 90% woodchips and 10% biochar (B10), and 70% woodchips and 30% biochar (B30). Simulated agricultural drainage with four unique concentration combinations of 16.1 and 4.5 mg L-1 NO3--N and 1.9 and 0.6 mg L-1 PO43--P was delivered at hydraulic retention times (HRTs) of 3, 6, and 12 h. Mean NO3--N removal efficiencies ranged from 16.9%-93.7%, and media type was insignificant at low influent NO3--N concentrations, but B30 was the most effective at high influent NO3--N concentrations. Mean PO43--P removal efficiencies ranged from -122.0%-74.9%, with B10 and B30 significantly worse than W at removing PO43--P. These findings corroborate previous work indicating boosted NO3--N removal with biochar, but contradict studies upholding PO43--P-removing capabilities. / Master of Science / Nitrogen and phosphorus-containing nutrients are applied to agricultural fields for supporting higher crop yields, and once these nutrients are exported they can negatively impact ecosystem biodiversity and water quality. These nutrients therefore require management. Denitrifying bioreactors (DNBRs) are subsurface engineered structures that intercept and treat agricultural drainage by supporting nitrate-removing denitrification with a carbon substrate. Recent studies have unearthed the potential of biochar, which is a type of charcoal typically used for soil amendment, as a substrate for promoting simultaneous removal of nitrogen and phosphorus. This study investigated biochar’s potential as an amendment to the traditional DNBR woodchip media using laboratory-scale DNBRs that were subjected to different hydraulic retention times and influent nutrient concentrations. Results revealed that the biochar did not significantly enhance nitrate removal under low influent nitrate concentrations, but did significantly improve nitrate removal at high influent nitrate concentrations. The biochar-amended treatments were significantly worse than the woodchip treatments at supporting phosphate removal. These findings suggest that biochar may indeed boost nitrate removal, but may not improve phosphate removal.

Landfill leachate characteristics vary depending on the operation type of the landfill and the age of the landfill. At landfills operated as bioreactors, where leachate recirculation is practiced, leachate ammonia nitrogen concentrations may accumulate to extremely higher levels than during single pass leaching, thereby requiring treatment before final discharge to a receiving system (Onay, 1998). Usually several physical/chemical wastewater treatment technologies are used to treat the leachate. In most cases the COD and BOD are treated, and then nitrification is performed in a separate sophisticated ex situ system. The additional costs of these systems can be very high. The use of a readily available media for in situ nitrification should be considered a prime objective to avoid extra costs. The possibility of removing ammonia nitrogen from bioreactor landfill leachate using trickling filter biofilm technology was studied in four laboratory scale reactors filled with four different types of packing media. The different packing media were examined to see which media is the most efficient at supporting ammonia removal biofilms. The highest efficiency was achieved by a packing media consisting of pine wood chips. The effects of varied concentration loading, varied hydraulic loading, and nitrification inhibitors were studied. Varied ammonia concentration did not have a huge impact on the ammonia removal rates (77-87%) in the reactor with pine wood media. The ammonia removal rates showed a strong dependence on hydraulic loading rate with the lowest loading rate producing the highest removal rates. Landfill leachate from the Middle Peninsula Landfill in Glens, Virginia was determined not to contain nitrifying inhibitors. Using a wood media filter chip and a low hydraulic loading rate was determined to be the best method to remove ammonia nitrogen from landfill bioreator leachate. / Master of Science

Yes / (1) Abdominal aortic aneurysm (AAA) is a silent, progressive disease with significant mortality from rupture. Whilst screening programmes are now able to detect this pathology early in its development, no therapeutic intervention has yet been identified to halt or retard aortic expansion. The inability to obtain aortic tissue from humans at early stages has created a necessity for laboratory models, yet it is essential to create a timeline of events from EARLY to END stage AAA progression. (2) We used a previously validated ex vivo porcine bioreactor model pre-treated with protease enzyme to create "aneurysm" tissue. Mechanical properties, histological changes in the intact vessel wall, and phenotype/function of vascular smooth muscle cells (SMC) cultured from the same vessels were investigated. (3) The principal finding was significant hyperproliferation of SMC from EARLY stage vessels, but without obvious histological or SMC aberrancies. END stage tissue exhibited histological loss of α-smooth muscle actin and elastin; mechanical impairment; and, in SMC, multiple indications of senescence. (4) Aortic SMC may offer a therapeutic target for intervention, although detailed studies incorporating intervening time points between EARLY and END stage are required. Such investigations may reveal mechanisms of SMC dysfunction in AAA development and hence a therapeutic window during which SMC differentiation could be preserved or reinstated. / This research was funded in part by The Leeds Teaching Hospitals Charitable Foundation (R11/8002). E.R.C. was supported by a PhD studentship from the Engineering and Physical Sciences Research Council (EPSRC; EP/F500513/1). R.J.H. was the recipient of an Intercalated Batchelor of Science Degree in Science award from the Royal College of Surgeons of England. M.A.B.(FS/18/12/33270 and FS/12/54/29671), K.I.B. (FS/12/26/29395), and K.J.G. (FS/11/91/29090) were supported by BHF Clinical Research Training Fellowships.

No description available.

The formation of bacterial biofilms on surfaces and their subsequent biofouling pose extensive safe and healthy concerns to a variety of industries. Biofilms are ubiquitous, and the biofilm state is considered the default mode of growth for the majority of the world's bacteria population. Once mature, biofilms are difficult to remove completely and have improved resistance against antibacterial agents. Given this, there has been significant interest to mitigate or at least manage biofilm formation on surfaces. One such method has been through the material design of surfaces, and to the interest of this study, through the development of antimicrobial stainless steels. Stainless steel is not an inherently antimicrobial material. Stainless steels alloyed with small amounts of either copper (Cu) or silver (Ag), both well-known natural antimicrobial agents, have been investigated since their initial development in the late 1990's onward. This class of materials have been proven to show significant antimicrobial effect over their traditional counterparts without compromising the characteristic mechanical properties of the stainless steels. However, most of the antimicrobial assessments for these materials documented within literature are conducted over a 24-hour timeframe and do not adequately account for the biofilm mode of growth. As so, this study aimed to assess how biofilms grow on this class of antimicrobial steels over a longer duration of growth and under growth conditions which more adequately modeled the biofilm mode of life. The same strain of Escherichia coli commonly used in antimicrobial surface testing, ATCC 8739, was grown on submicron-polished coupons of a ferritic Cu-alloyed stainless steel (1.50 wt. % Cu), an austenitic Ag-alloyed stainless steel (0.042wt. % Ag), and a standard 304 series stainless steel, used as a baseline. Following ASTM-E2647-13, the E. coli/SS coupons were grown using a drip flow bioreactor under low shear conditions at either ambient temperature or 37 ± 3 degrees C with a batch phase of 6 hours and a continuous phase of 48 hours up to 96 hours. Directly after harvesting, the coupons were analyzed with an Environmental Scanning Electron Microscope (E-SEM) under low vacuum with a water vapor environment. The effect of surface chemistry and alloy microstructure, surface roughness, rinsing the surfaces prior to inoculation and after harvesting, temperature, and growth duration on the resulting E. coli biofilms were all investigated in some capacity. Growth on the submicron finished surfaces indicated there were no significant differences between the biofilms grown on the three different steel compositions. Bacterial attachment appeared non-preferential to surface chemistry or alloy microstructure, suggesting that E. coli interacted with the surfaces effectively the same under the given growth conditions. To account for apparent randomness in bacterial attachment, it is hypothesized that the surface features of interest were on a size scale irrelevant to the size of single bacterial cells. To account for the lack of an observed biocidal effect from the Cu- and Ag-alloyed stainless steels, it is hypothesized that an organic conditioning film which developed on the surfaces from the fluid environment may have effectively inhibited the release of Cu and Ag ions from the steel surfaces. / MS / Bacteria frequently self-organize into what are commonly called bacterial biofilms, or an aggregation of bacterial cells that attach to a surface and which are embedded within a self-generated matrix of polymeric substances, such as proteins and polysaccharides. The biofilm state offers a lot of survival advantages to bacteria, and once biofilms form on a surface they are very difficult to remove. The formation of bacterial biofilms on surfaces and their subsequent biofouling pose extensive safe and healthy concerns to a variety of industries. There has been significant interest to stop or at least manage biofilm formation on surfaces. One such method has been through the design of surfaces, and to the interest of this study, through the development of antimicrobial stainless steels. Stainless steel is not an inherently antimicrobial material. Stainless steels which include small amounts of either copper or silver have been proven to show a significant antimicrobial effect over their traditional stainless steel counterparts without compromising the other desirable properties of the steels. However, most of the documented antimicrobial assessments for these materials have been conducted over a 24-hour timeframe and do not adequately account for the biofilm mode of growth. This study aimed to assess how biofilms grow on this class of steels over a longer duration of growth and under growth conditions which more adequately modeled the biofilm mode of life. This was done by growing a single strain of E. coli bacteria onto coupons of these stainless steel materials for either a 48-hour or a 96-hour timeframe within a low-flow, continuously-fed bioreactor. The coupons were visualized with an environmental scanning electron microscope to assess the effect of the material properties on the observed biofilms grown during this study. Overall there were little differences observed between the E. coli biofilms grown on the copper-containing stainless steel, the silver-containing stainless steel, and the standard stainless steel used within this study. Mirror finish smooth surfaces were needed in order to adequately visualize the steel coupons. The bacteria appeared to attach randomly without any preference for steel surface chemistry or other surface features. This suggested that under the given growth conditions the bacteria interacted with the smooth steel surfaces the same. To account for this randomness, it is hypothesized that the relevant surface features were significantly smaller than the size of single bacterial cells. E. coli cells are between 1 – 2 micrometers long and 0.5 – 1 micrometers in diameter. There was also no antimicrobial effect observed on the copper-containing and silver-containing stainless steels. To account for the lack of an observed antimicrobial effect, it is hypothesized that a conditioning film of carbon-based molecules formed on the surface of the steels from the liquid growth medium environment, preventing bacterial cells from being damaged by the copper and silver within the steel surfaces.

<p dir="ltr">Dynamically shape morphing devices have emerged as pivotal tools in various fields, bridging the gap between static structures and adaptive systems capable of real-time reconfiguration. These devices hold significant potential for revolutionizing human-machine interfaces, enhancing cell mechanobiology, and innovating within the realm of optical and acoustic metamaterials. The core challenge in developing these devices lies in their requirement for a complex array of actuators and a sophisticated control strategy that precisely calculates the necessary actuator stimulations to achieve targeted surface morphologies.</p><p dir="ltr">In this dissertation, I introduce a novel approach to the control of shape morphing devices through a model-free control system utilizing ML. This system allows for precise control over morphing surfaces by deciphering the intricate internal couplings within actuator arrays. Our approach markedly contrasts with traditional methods that rely heavily on pre-defined mechanical configurations and linear control strategies, which are often limited in their adaptability and responsiveness.</p><p dir="ltr">I demonstrate the efficacy of this control method through various applications, including programmable 2.5D surfaces that can dynamically morph into complex shapes based on predefined designs. In order to achieve miniaturization of the control system, passive matrix addressing is introduced for the morphing surface constructed from ionic actuator arrays. This innovative addressing method significantly reduces the number of necessary control inputs from $N^2$ to $2N$ where $N$ represents the number of actuators along one dimension of the array. This reduction not only simplifies the hardware requirements but also enhances the scalability and potential integration of these devices into more compact and complex environments. The precision and programmability of both forward and inverse control offered by our model-free ML approach are shown to be superior in handling the nonlinearities and interdependencies within the actuator arrays, providing a robust platform for developing highly customizable shape morphing interfaces.</p><p dir="ltr">Furthermore, the same methodology can be employed to customize strain fields, which have broad applications in bioreactors. Initially, a non-equibiaxial cell stretcher using pneumatic actuators was developed to validate the critical role of complex strain fields in biomechanics. The ability to dynamically alter the mechanical stress experienced by cells in vitro can lead to improved understanding and enhancement of tissue engineering and regenerative medicine practices. Additionally, to customize the strain field, a machine learning-based image processing method is proposed to control dielectric elastomer actuator arrays, enabling the customization of complex strain fields. This approach provides a potential testbed for tumor biomechanics research by replicating identical strain fields based on tumor shapes.</p><p dir="ltr">The implications of this research are profound, suggesting a paradigm shift in how dynamic systems can be controlled and utilized across various scientific and engineering disciplines. The integration of ML into the control of physical actuation systems opens up new possibilities for the adaptive and intelligent design of morphing structures, potentially leading to more intuitive and responsive interfaces that could transform everyday human-technology interactions.</p>

Advancements in regenerative medicine have opened new possibilities for treating cardiovascular diseases. Using stem cell-derived cardiac cells has shown great promise in regenerating damaged heart tissue. However, the efficacy of this approach is limited by the inability to culture, differentiate, and mature these cells in a controlled and efficient manner. This work addresses some of these challenges by developing new tools and techniques for the culture and differentiation of human stem cell-derived cardiomyocytes. To address the above issues, we developed a novel bioreactor to deliver electrical stimulation and fluid mixing for enhanced nutrient transfer to improve the differentiation and maturation of stem cell-derived cardiomyocytes. This bioreactor was designed using computation modeling to optimize the applied electrical stimulation and fluid flow and constructed using low-cost, 3D-printed materials. Electrical stimulation in the bioreactor improves the differentiation and maturation of cardiomyocytes. Specifically, we tested how electrical stimulation can influence the subtype determination of stem cell-derived cardiomyocytes in vitro. In addition, we have developed conductive biomaterials in the form of transparent conductive films and conductive nanofibers to further aid in the maturation of cardiomyocytes. Overall, this study represents a significant step forward in developing new tools and techniques for the culture and differentiation of stem cell-derived cardiac cells. The bioreactor and conductive biomaterials developed in this study have the potential to improve the efficiency and effectiveness of stem cell-based therapies for the treatment of cardiovascular diseases, and the results of electrical stimulation experiments provide essential insights into the optimal stimulation parameters for the differentiation and maturation of stem cell-derived cardiac cells. Further research is needed to optimize these techniques and translate them into clinical practice, but this study provides an important foundation for future work in this area. / Bioengineering / Accompanied by one .zip file : 1) Licata_temple_0225E_171Supplemental_Videos.zip

Klädindustrin är idag en stor bidragande orsak till negativa miljöpåverkningar. Om avtrycket från den industrin ska minska behöver det ”fast fashion” fasas ut och ett nytt sätt att se på kläder implementeras. De enklaste sätten att minska avtrycket är att återanvända eller återvinna kläder. Renewcell återvinner textilier och bryter ner bomullen och återvinner den som nytt material - Circulose®. Det materialet skickas vidare för att bli nya kläder och på så sätt stängs loopen för textilindustrin. Av produktionen av Circulose® tillkommer ett nytt slags processavlopp som inte hunnits forskas mycket på. Paralleller till textilindustrin kan visserligen dras och där är processavloppen av heterogen karaktär. Renewcell vill se om det går att reducera det organiska materialet i avloppet till en nivå på 10 mg/l. Den här studien vill hjälpa till att fylla det forskningsgap som finns för reningsteknik inom textilåtervinningsindustrin idag. Med en ny marknad i uppstart är det viktigt att avlopp hanteras på ett bra och ansvarsfullt sätt. Syftet med studien var att undersöka experimentellt och litterärt om det går att reducera ner BOD7 i Renewcells processavloppet till 10 mg/l. En MBBR har efterforskats och jämförts med en MBR, där en MBBR ansågs vara mer resistent mot variationer och farliga ämnen. Det byggdes en MBBR i laborationsskala kopplat till processavloppet för att analysera reduktionen av BOD7 och för att göra en experimentell undersökning hur den kemiska fällningen påverkas om vattnet behandlades biologiskt först. Studien resulterade i att Renewcells karaktär på processavlopp är heterogent och är hanterbart av mikroorganismer. Dock, på grund av att ingen fullt utvecklad biofilm nåddes samt variationer i processen är det fortfarande osäkert om det fungerar att implementera en MBBR hos Renewcell. Processförändringar som ett produktionsstopp är inga problem för en fullt utvecklad MBBR att hantera. Processavloppet innehåller en stor mängd organiskt material, men saknar tillräckligt med näringsämnen. För detta projekt var 58 % reduktion av BOD7 den högsta som redovisades och det nåddes inte heller en fullt utvecklad biofilm. Att biologiskt behandla avloppet innan en kemisk fällning gav positiva resultat då reduktionen av metalljoner förbättrades. Allt som allt anses det vara möjligt att implementera en MBBR hos Renewcell om rätt förutsättningar finns och det ges en möjlighet att utveckla en biofilm fullt ut. Förhoppningsvis kan denna förstudie visa vägen för vidare studier inom området. / The clothing industry is one of the major causes for negative environmental impacts. The “fast-fashion” needs to be phased out and a more climate-friendly way of using clothes implemented. The easiest ways to do this is to reuse or recycle clothes. Renewcell recycles used textiles and dissolve the cotton into pulp and makes a new material of it - Circulose®, which is sent to become new clothes and, in that way, helps to close the loop for textile industry. With the production of Circulose® a new kind of wastewater is produced which has not yet been thoroughly researched. A parallel to the textile industry’s wastewater can be drawn, and that is of heterogeneous nature and can change quickly from day to day. It is in Renewcell’s interest to reduce the organic matter in the wastewater, more than they do today with their current chemical and mechanic wastewater treatment plant does. This study wants to help fill the research gap that exists for purification technology in the textile recycling industry today. Since it is a new field of technology, it is of importance to thoroughly invest in how to treat the wastewater responsibly. The purpose of this study was to investigate, both experimentally and literary, whether the possibility to reduce BOD7 to 10 mg/l in the wastewater treatment plant. With an investigation of MBBR and by compare it with an MBR it was concluded that a MBBRis a better fit for Renewcell since it is considered to be more resistant to variations and hazardous substances. To strengthen that conclusion a MBBR in laboratory scale was built and wastewater directly from the recycling process treated. The reduction of BOD7 and how it would come to affect the chemical precipitation was analyzed. The results of the study concluded that Renewcells wastewater is heterogenous and manageable for microorganisms. However, the due to the variations in the process such as dosing of biologically harmful substances it might not be possible for Renewcell to implement a MBBR. Process variations as a stop in production of wastewater for a shorter time period is manageable. The wastewater contains enough organic matter, but an extra addition of nutrients is needed. For this project the MBBR-process fluctuated in reduction of organic matter and the highest amount achieved was 58 %. No fully developed biofilm was achieved either. Biologically treating the process effluent before the chemical precipitation gave positive results as the reduction of metal ions was improved. All in all, it is believed to be possible to implement a MBBR at Renewcell if the process is given the required conditions from the beginning and a biofilm can be fully developed. Hopefully, this pilot study can show the way for future research within the field.

Doctor of Philosophy / Department of Grain Science and Industry / Praveen V. Vadlani / The purpose of this study was to investigate micro- and macro-scale aspects of solid state fermentation (SSF) for production of cellulolytic enzymes using fungal cultures. Included in the objectives were investigation of effect of physicochemical characteristics of substrate on enzymes production at micro-scale, and design, fabrication and analysis of solid-state bioreactor at macro-scale. In the initial studies response surface optimization of SSF of soybeans hulls using mixed culture of Trichoderma reesei and Aspergillus oryzae was carried out to standardize the process. Optimum temperature, moisture and pH of 30ºC, 70% and 5 were determined following optimization. Using optimized parameters laboratory scale-up in static tray fermenter was performed that resulted in production of complete and balanced cellulolytic enzyme system. The balanced enzyme system had required 1:1 ratio of filter paper and beta-glucosidase units. This complete and balanced enzyme system was shown to be effective in the hydrolysis of wheat straw to sugars. Mild pretreatments– steam, acid and alkali were performed to vary physicochemical characteristics of soybean hulls – bed porosity, crystallinity and volumetric specific surface. Mild nature of pretreatments minimized the compositional changes of substrate. It was explicitly shown that more porous and crystalline steam pretreated soybean hulls significantly improved cellulolytic enzymes production in T. reesei culture, with no effect on xylanase. In A. oryzae and mixed culture this improvement, though, was not seen. Further studies using standard crystalline substrates and substrates with varying bed porosity confirmed that effect of physicochemical characteristics was selective with respect to fungal species and cellulolytic activity. A novel deep bed bioreactor was designed and fabricated to address scale-up issues. Bioreactor’s unique design of outer wire mesh frame with internal air distribution and a near saturation environment within cabinet resulted in enhanced heat transfer with minimum moisture loss. Enzyme production was faster and leveled within 48 h of operation compared to 96 h required in static tray. A two phase heat and mass transfer model was written that accurately predicted the experimental temperature profile. Simulations also showed that bioreactor operation was more sensitive to changes in cabinet temperature and mass flow rate of distributor air than air temperature.

Thesis (MEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: See PDF for abstract. / AFRIKKANSE OPSOMMING: Sien PDF vir die opsomming.