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Enhancing Microalgal Biomass Growth and Nutrient Removal in Anaerobic Digestate
No full textMicroalgal treatment of anaerobic digestate has attracted research attention due to algae’s capability for nutrient removal and recovery. However, microalgae rarely tolerate full-strength anaerobic digestate, and this problem is frequently handled with dilution. According to the literature, it has been hypothesized that high ammonia, turbidity, and heavy metals are the main inhibitors. However, our previous research suggested that additional inhibitors may be even more important. In past work, we developed a pretreatment method using aerobic bacteria that alleviated algal inhibition, and we hypothesized that inhibitory organic compounds are present in digestate. This approach enables algae to reach very high culture densities before nutrients are exhausted from the digestate. When algae reach a high density, light penetration diminishes, slowing down or halting growth before all the nutrients are fully removed from the digestate. This results in incomplete nutrient recovery and limits the efficiency of the process. To address this issue, implementing multi-stage algae cultivation can help maintain optimal growth conditions, allowing for nutrient removal to occur over multiple batches of algae growth and enhancing the overall effectiveness of the treatment system.
In the first chapter of this study, we aim to 1) develop two different pretreatment strategies (activated sludge and biochar pretreatment) and test their alleviation of inhibition, 2) determine metabolites that are removed during pretreatment using LCMS-MS and 3) Analyze the inhibitory effect of identified metabolites on the growth of algae using a dose-response approach. Both pretreatments significantly enhanced biomass productivity (412 mg L-1 d-1 after activated sludge pretreatment, 292 mg L-1 d-1 in biochar pretreatment, and only 40 mg L-1 d-1 without pretreatment, P < 0.05). Additionally, total nitrogen removal efficiency was 63%, 21%, and 5% with activated sludge pretreatment, biochar pretreatment, and no treatment, respectively. LCMS-orbitrap analysis revealed the removal of many phenolic compounds, antibiotics, and animal hormone metabolites after pretreatment, and we showed that six of the twelve compounds tested are inhibitory to algae at < 1 mg L-1 levels in dose-response trials (Butylparaben, Salicylic acid, Bisphenol A, Bisphenol F, Tiamulin, Androsterone).
In the second chapter, we developed and tested a two-stage semi-continuous reactor system (two sequencing reactors with clarifiers) for long-term algal cultivation in pretreated anaerobic digestate, aiming to enhance nutrient removal efficiency and biomass yield over single-stage systems. Results indicate that the multi-stage reactor setup improves nutrient recovery and mitigates light limitations due to high cell density, a common limitation in single-stage systems. This study achieved some of the highest algae productivities ever achieved on full-strength anaerobic digestate (0.59-0.78 g L-1 d-1 and 0.15-0.92 g L-1 d-1 for stages 1 and 2, respectively). Plus, adding a second stage of algae cultivation enabled significant (P<0.05) additional N and P removal, resulting in an unprecedented 95% reduction in influent NH4-N, reducing the value from ~2,400 mg L-1 to <200 mg L-1. P was also reduced from ~550 mg L-1 to ~100 mg L-1 across the multi-stage process.
Overall, this study suggests that organic compounds in digestate are important inhibitors of algal growth and shows the effectiveness of the two pretreatments in removing them. This study also contributes to developing sustainable waste-to-resource strategies, highlighting the potential of algae cultivation to treat nutrient-rich waste streams while producing high-value biomas
Does Access Imply Usability? Evaluating Social and Physical Barriers to Park Access and Usability within Atlanta, Georgia
Get PDFThe mere existence of green spaces doesn't guarantee their usage, and access to them isn't solely dependent on their proximity. This study investigates park use in Atlanta, Georgia with a focus on understanding how park accessibility and usability as well as green infrastructure implementation impact overall park use. Four parks in Atlanta were selected for this study and represented diverse urban characteristics as well as socioeconomically distinct block groups. A mixed-methods comparative case study analysis, including in-situ observations, user surveys, and geospatial analysis was employed to assess contributions and barriers of both usability and accessibility. Findings from this study indicate that parks in low-income and minority neighborhoods face more challenges to park usability while parks located in higher-income areas with well-maintained green infrastructure have increased usability and accessibility. As urban areas, like Atlanta, Georgia begin to implement additional sustainable measures to combat the effects of the urban heat island, addressing barriers to park usability within urban parks becomes essential. Findings from this study highlight the importance of creating inclusive and enjoyable green spaces for all communities
THE USE OF SUPPLEMENTAL FEED IN PASTURE-BASED STOCKER CATTLE SYSTEMS FOR INCREASED NUTRIENT CYCLING
Get PDFIn Alabama, pasture-based beef cattle operations are prevalent, but all-time high fertilizer costs present challenges to production. The objective of this research was to evaluate nutrient cycling through supplemental feeding or addition of legumes. Stocker steers (n = 60) were used in a put-and-take grazing and supplementation study, arranged as a generalized complete block design across two locations. Treatments included 0.5 or 1.0% BW supplemental feed (SUP0.5 or SUP1.0, respectively), interseeded red clover (CLOV), or a negative control (tall fescue pasture only; CON). There was an effect of treatment (P ≤ 0.01) for ADG and gain per hectare, but not for forage mass (P = 0.84) or soil pH, OM, N, P, K, or microminerals (P ≥ 0.22). Results are interpreted to mean that the one-year scale of stocker supplementation may not offset chemical fertilizer inputs, though partial budgets indicated increased revenue
Mechanistic Determinations of Enhanced Heat Transfer Occurring in Stagnant and Flowing Microfibrous Entrapped Catalytic Reactors
No full textMicrofibrous media (MFM) is a fibrous material made via traditional paper-making
techniques resulting in a media that is preferentially oriented within a single plane (but
random within that plane). Metal MFMs, particularly copper MFM (Cu-MFM), are used
in catalytic beds and are known to exhibit superior heat transfer performance to packed
beds. To investigate the mechanisms for this, experiments were conducted in an 1
8-inch
alumina pellet packed bed and a Cu-MFM bed composed of 17 mm diameter x 6 mm long
fibers and 6 mm diameter x 3 mm long fibers. Heat transfer experiments were performed
both with stagnant and flowing gasses as well as under vacuum. Existing literature models
were compared to the experimental results and various resistance networks and unit cells
are presented for modelling MFM. What was found is that the the presence of a gas within
an MFM bed plays a substantial role in its effective thermal conductivity. Additionally, as
has been previously shown for packed beds, as the thermal conductivity of the gas within
an MFM bed increases, the effective thermal conductivity of the bed increases. It was
found that if two fibers are modelled with a gas-filled gap, the length of the gap has a
large impact on the effective thermal conductivity of the system. Therefore, it is proposed
that the superior heat transfer performance of MFM over packed beds is due in part to the
preferential orientation of the fibers as appears in prior literature, and in part due to many
short gaps between fibers within the media that, when a fluid is present, provide excellent
heat-transfer pathways
Design for Emotional Durability: Investigating the Relationship between Emotions and Product Longevity in Industrial Design
No full textThe focus of this thesis is the investigation of the connection between product emotion and durability in industrial design, as well as how emotions can affect product attachment and durability, and proposing a framework for integrating emotional durability into the product development process. This study investigates the definitions of symbolic meanings, aesthetic emotions and other related factors that play a key role in product longevity, introducing a design tool related to emotional durability to design projects. The research findings imply that designing for emotional durability necessitates a deeper comprehension of how products can act as archives of symbols, identities, and values that are effectively communicated through form, materiality, and function. With the help of this new methodology, it is possible to design products that are not only useful, beautiful and emotionally appealing but also meaningful and long-lasting
Role of IFN-λ in Herpes Simplex Virus-1-induced corneal Immunopathology
No full textThe Herpes simplex virus (HSV) is a highly successful pathogen in the Herpesviridae family, consisting of eight enveloped human herpesviruses. These double-stranded DNA viruses with similar morphology can reactivate latent infection and develop productive lytic infections. HSV-1, a highly prevalent pathogen, spreads through close contact and causes lifelong infections. It can cause asymptomatic, mild, or fatal illnesses. The annual medical, social, and financial costs of HSV infection exceed $400 million in the USA. Anti-HSV medications like acyclovir, valacyclovir, penciclovir, and famciclovir effectively treat herpes virus infections. Still, they have hazardous side effects and are not effective in treating drug-resistant variants. Despite years of research, no approved vaccinations are available for prevention or therapy.
HSV-1 infection of the cornea causes a severe immunoinflammatory and vision-impairing condition called herpetic stromal keratitis (SK). The virus replication in corneal epithelium, followed by neutrophil- and CD4+ T cell-mediated inflammation, plays a dominant role in SK. Although previous studies demonstrate critical functions of type I IFNs (IFN-α/β) in HSV-1 infection, the role of recently discovered IFN-λ (type III IFN), specifically at the corneal mucosa, is poorly defined. Our study using a mouse model of SK pathogenesis shows that HSV-1 infection induces a robust IFN-λ response compared with type I IFN production at the corneal mucosal surface. However, the normal progression of SK indicates that the endogenous IFN responses are insufficient to suppress HSV–1-induced corneal pathology. Therefore, we examined the therapeutic efficacy of exogenous rIFN-λ during SK progression. Our results show that rIFN-λ therapy suppressed inflammatory cell infiltration in the cornea and significantly reduced the SK pathologic condition. Early rIFN-λ treatment significantly reduced neutrophil and macrophage
3
infiltration and IL-6, IL-1
β, and CXCL-1 production in the cornea. Notably, the viricidal capacity of neutrophils and macrophages measured by reactive oxygen species generation was not affected. Similarly, ex vivo rIFN-λ treatment of HSV-1-stimulated bone marrow-derived neutrophils significantly promoted IFN-stimulated genes without affecting reactive oxygen species production. Collectively, our data demonstrate that exogenous topical rIFN-λ treatment during the development and progression of SK could represent a novel therapeutic approach to control HSV–1–induced inflammation and associated vision impairment.
RNA-seq analysis has transformed gene expression research by enabling extensive and precise quantitative measurements. This study showcased the potential of RNA-seq in comprehending gene regulation during corneal HSV-1 infection following exogenous rIFN-λ therapy. We employed DESeq2 analysis to compare gene expression levels between corneas infected with HSV-1 and corneas treated with rIFN-λ. We elucidated the antiviral and anti-inflammatory mechanism of rIFN-λ in the context of corneal HSV-1 infection in mice, confirming previous studies on the therapeutic effects of IFN-λ against HSV-1.
Prolonged treatment with acyclovir (ACV), a preferred systemic therapy against HSV-1 infection, often leads to the development of HSV-1 strains resistant to ACV. In this study, we generated and characterized ACV-resistant (ACVR) HSV-1 (McKrae), a neurotropic strain that mimics the clinical HSV-1 infection caused by an ACV-resistant strain. This virus was utilized to check the effectiveness of IFN-λ in inhibiting ACVR HSV-1. We found that IFN-λ effectively inhibits the formation of matured virus particles
Insights into Sintering of Metallic Nanoparticles Using Molecular Dynamics Simulations: Implications for Additive Nanomanufacturing
No full textAdditive nanomanufacturing, which utilizes laser-induced nanoparticle (NP) ablation and sintering, offers a versatile approach for fabricating novel electronic devices with unique properties. This technique allows for tunable composition and porosity state of the sintered material, as well as compatibility with various substrates, including biodegradable ones. However, achieving desired sintering without damaging the substrate requires careful control of laser energy input and duration. The porosity state of the sintered material, which determines its properties such as the electronic circuit resistivity, depends not only on temperature (determined by laser energy input) but also on NP size, size ratio, crystallographic misorientation, material type, and miscibility.
To gain a quantitative understanding of these dependencies, this dissertation work employs molecular dynamics simulations to investigate the sintering behavior of monometallic NP doublets (silver and copper) and bimetallic NP doublets (silver-copper and silver-gold) at varying temperatures. It analyzes the influence of NP size, size ratios, misorientation angles (tilt and twist), material type (comparing silver and copper), and miscibility (comparing silver-copper and silver-gold) on the sintering outcomes. Based on the results, a mathematical framework to describe the characteristic sintering time; the time required for monometallic/bimetallic NP doublets to reach specific normalized neck sizes has been proposed. Additionally, the formation and evolution of crystallographic defects (vacancies, dislocations, stacking faults, twin boundaries, and grain boundaries) during sintering are explored to elucidate the underlying sintering mechanisms, such as crystallographic defect-mediated and surface-mediated diffusion processes.
Keywords: Additive nanomanufacturing; Sintering; Nanoparticles; Molecular dynamics; Crystallographic defect
Estimation of State of Charge and State of Health for Cylindrical Lithium-ion Battery with C-Si Anode
No full textAccurate measurement of the state of charge (SOC) and state of health (SOH), including capacity fade (SOHQ) and power fade (SOHP) that predicts the energy and power of the remaining lifespan of the battery is the core task in the battery management system (BMS). Since SOC and SOH are not directly measured, their estimation is predominantly executed based on the battery models. The models can be either based on an electrochemical model that considers chemical reactions in the battery or an equivalent circuit model (ECM). The latter is used more because of the low computational time and less complexity in its parameter identification. On the other hand, the anode materials are enhanced from carbon only to the carbon-silicon to increase energy density and theoretical capacity. However, silicon induces an extremely high volume change compared to carbon, which leads to the open circuit voltage (OCV) gap between charge and discharge at specific SOC. In fact, OCV is the most crucial parameter for estimating SOC since the OCV gaps and associated errors lead to inaccurate estimations of SOC and SOH. Therefore, a second-order ECM with hysteresis (ECMwH) representing the mechanical stress model is proposed. Based on the model, the capacity and internal resistance are estimated using two extended Kalman filters (EKF). The proposed algorithms are validated with an NCA/C-Si 21700 cylindrical cell with a nominal capacity of 5.3Ah using multiple charge-discharge test profiles under various temperatures and varying aging cycles. With this proposed method, the estimated results indicate less than 2.5% SOC estimation root mean square error (RMSE) and 2.1mV terminal voltage RMSE, which demonstrates a 3% SOC RMSE improvement compared to average OCV based method. SOHQ is estimated to have 0.43% RMSE. The estimation of SOHP is also validated. The results have shown that overall estimation tends to follow the measured values; however, errors increase as the SOC decreases
The Relationship of Medial Longitudinal Arch Stiffness and Mechanics of The Approach to Sprint Termination
No full textThis project explores the impact of Medial Longitudinal Arch (MLA) stiffness, measured both barefoot and in shoes, on biomechanics during the approach to sprint termination in males and females. During this phase, increased vertical loading is observed, with the MLA acting as a spring to manage force absorption. The primary objectives were twofold: first, to investigate the association between MLA stiffness and spatiotemporal characteristics; second, to examine the relationship between MLA stiffness and lower extremity stiffness during the approach to sprint termination. Key findings indicate that increased MLA flexibility correlates with extended braking times in males, although no significant associations were found for lower extremity stiffness. However, no significant associations were found between MLA stiffness and lower extremity stiffness for either sex, highlighted by variability influenced by approach strategies. In conclusion, while MLA functionality appears integral to sub-phase duration of the approach to sprint termination, further investigation into movement strategies, influenced by motor abilities and task requirements, is crucial to fully elucidate their interplay with lower extremity mechanics in this context
Unmuting the Mic on Telework: The Development and Validation of Telework OCB and CWB Scales
Get PDFThis paper proposes the development and validation of two new scales for measuring telework organizational citizenship behaviors (T-OCBs) and telework counterproductive workplace behaviors (T-CWBs). These scales are being created to address the unique behaviors that teleworkers might engage in that are unique manifestations from traditional work environments. The development process involves the formulation of a set of new items generated from the ground up through a multitude of methods to fully capture the conceptual domain that is T-OCB and T-CWB. These items were then evaluated for their validity, and a new scale is presented