The gaseous species concentration of Jet A-1, GTL, CTL and a blend of 80 vol.% GTL and 20 vol.% hexanol jet fuels in laminar coflow diffusion flames have been measured and studied. These species are carbon monoxide, carbon dioxide, oxygen, methane, ethane, ethylene, propylene, and acetylene. Benzene and propyne concentrations were also detected in CTL flames. 1-Butene has been quantified for the blend of GTL and hexanol flame. The detailed experimental setup has been described and results from different flames are compared. The CO is produced in a same amount in all the flames. The CTL flame had the largest and GTL/hexanol flame had lowest CO2 concentrations. The results indicate that GTL and GTL hexanol blend flames produce similar concentrations for all the measured hydrocarbon species and have the highest concentration among all the jet fuels. The experimental results from Jet A-1 fuel are also compared with numerical studies by Saffaripour et al.

Driving with the cold engine increases fuel consumption and greenhouse gases emissions. A latent heat energy storage device has been proposed to recover waste heat and reduce engine warm-up time by using phase change materials (PCMs) as an energy storage medium. Two types of paraffin waxes and 50/50 mixture of the two have been examined to characterize their behaviors under repetitive heating/freezing. From the results, the heat transfer is more effective in the case of narrower spacing distances between the cooling plates and high circulating flow rate of the heat transfer fluid. A 50/50 mixture of two paraffin waxes also provides better heat transfer due to the possible existence of both conduction and natural convection. The results of the metal block simulation experiments demonstrated the potential of latent heat TES’s for use in engine warm-up.

Despite the increasing clinical demand in reconstructive, cosmetic and correctional surgery there remains no optimal strategy for the regeneration or replacement of adipose tissue. Previous approaches to adipose tissue engineering have failed to create an adipose tissue depot that maintains implant volume in vivo long-term (>3 months). This is due to inadequate mechanical properties of the biomaterial and insufficient vascularization upon implantation. Modular tissue engineering is a means to produce large volume functional tissues from small sub-mm sized tissues with an intrinsic vascularization. We first explored the potential of a semi-synthetic collagen/poloxamine hydrogel with improved mechanical properties to be used as the module biomaterial. We found this biomaterial to not be suitable for adipose tissue engineering because it did not support embedded adipose-derived stem cell (ASC) viability, differentiation and human microvascular endothelial cell (HMEC) attachment. ASC-embedded collagen gel modules coated with HMEC were then implanted subcutaneously in SCID mice to study its revascularization potential. ASC cotransplantation was shown to drive HMEC vascularization in vivo: HMEC were seen to detach from the surface of the modules to form vessels containing erythrocytes as early as day 3; vessels decreased in number but increased in size over 14 days; and persisted for up to 3 months. Early vascularization promoted fat development. Only in the case of ASC-HMEC cotransplantation was progressive fat accumulation observed in the module implants. Although implant volume was not maintained, likely due rapid collagen degradation, the key result here is that ASC-HMEC cotransplantation in the modular approach was successful in creating vascularized adipose tissue in vivo that persisted for 3 months. The modular system was then studied in vitro to further understand ASC-EC interaction. Coculture with ASC was shown to promote an angiogenic phenotype (e.g. sprouting, migration) from HUVEC on modules. RT-PCR analysis revealed that VEGF, PAI-1 and TNFα was involved in ASC-EC paracrine signalling. In summary, ASC-HMEC cotransplantation in modules was effective in rapidly forming a vascular network that supported fat development. Future work should focus on further elucidating ASC-EC interactions and developing a suitable biomaterial to improve adipose tissue development and volume maintenance of engineered constructs.

Pluripotent stem cells provide the opportunity to study human cardiogenesis in vitro, and are a renewable source of tissue for drug testing and disease models, including replacement cardiomyocytes that may be a useful treatment for heart failure. Typically, differentiation is initiated by forming spherical cell aggregates wherein an extraembryonic endoderm (ExE) layer develops on the surface. Given that interactions between endoderm and mesoderm influence embryonic cardiogenesis, we examined the impact of human embryonic stem cell (hESC) aggregate size on endoderm and cardiac development. We first demonstrated aggregate size control by micropatterning hESC colonies at defined diameters and transferring the colonies to suspension. The ratio of endoderm (GATA-6) to neural (PAX6) gene and protein expression increased with decreasing colony size. Subsequently, maximum mesoderm and cardiac induction occurred in larger aggregates when initiated with endoderm-biased hESCs (high GATA-6:PAX6), and in smaller aggregates when initiated with neural-biased hESCs (low GATA-6:PAX6). Additionally, incorporating micropatterned aggregates in a stirred suspension bioreactor increased cell yields and contracting aggregate frequency. We next interrogated the relationship between aggregate size and endoderm and cardiac differentiation efficiency in size-controlled aggregates, generated using forced aggregation, in defined cardiogenic medium. An inverse relationship between endoderm cell frequency (FoxA2+ and GATA6+) and aggregate size was observed, and cardiogenesis was maximized in mid-size aggregates (1000 cells) based on frequency of cardiac progenitors (~50% KDRlow/C-KITneg) on day 5 and cardiomyocytes (~24% cTnT+) on day 16. To elucidate a relationship between endoderm frequency and cardiac differentiation efficiency, aggregates were initiated with varying frequencies of ExE progenitors (SOX7-overexpressing hESCs). Maximum cardiomyocyte frequencies (~27%) occurred in aggregates formed with 10 to 25% ExE progenitors. These findings suggest a geometric relationship between aggregate size and ExE differentiation efficiency subsequently impacts cardiomyocyte yield, elucidating a mechanism for endogenous control of cell fate through cell-cell interactions in the aggregate.

The gaseous species concentration of Jet A-1, GTL, CTL and a blend of 80 vol.% GTL and 20 vol.% hexanol jet fuels in laminar coflow diffusion flames have been measured and studied. These species are carbon monoxide, carbon dioxide, oxygen, methane, ethane, ethylene, propylene, and acetylene. Benzene and propyne concentrations were also detected in CTL flames. 1-Butene has been quantified for the blend of GTL and hexanol flame. The detailed experimental setup has been described and results from different flames are compared. The CO is produced in a same amount in all the flames. The CTL flame had the largest and GTL/hexanol flame had lowest CO2 concentrations. The results indicate that GTL and GTL hexanol blend flames produce similar concentrations for all the measured hydrocarbon species and have the highest concentration among all the jet fuels. The experimental results from Jet A-1 fuel are also compared with numerical studies by Saffaripour et al.

Driving with the cold engine increases fuel consumption and greenhouse gases emissions. A latent heat energy storage device has been proposed to recover waste heat and reduce engine warm-up time by using phase change materials (PCMs) as an energy storage medium. Two types of paraffin waxes and 50/50 mixture of the two have been examined to characterize their behaviors under repetitive heating/freezing. From the results, the heat transfer is more effective in the case of narrower spacing distances between the cooling plates and high circulating flow rate of the heat transfer fluid. A 50/50 mixture of two paraffin waxes also provides better heat transfer due to the possible existence of both conduction and natural convection. The results of the metal block simulation experiments demonstrated the potential of latent heat TES’s for use in engine warm-up.

This study explores the possibility of utilizing bioleaching techniques for nickel extraction from a mixed sulfide ore deposit with high magnesium content. Due to the ultramafic nature of this material, well-studied bioleaching technologies, which rely on acidophilic bacteria, will lead to undesirable processing conditions. This is the first work that incorporates nitrate-dependent bacteria under pH 6.5 environments for bioleaching of base metals. Experiments with both defined bacterial strains and indigenous mixed bacterial cultures were conducted with nitrate as the electron acceptor and sulfide minerals as electron donors in a series of microcosm studies. Nitrate consumption, sulfate production, and Ni released into the aqueous phase were used to track the extent of oxidative sulfide mineral dissolution; taxonomic identification of the mixed culture community was performed using 16S rRNA gene sequencing. Nitrate-dependent microcosms that contained indigenous sulfur- and/or iron-oxidizing microorganisms were cultured, characterized, and provided a proof-of-concept basis for further bioleaching studies.

Embryonic stem cells (ESCs) are derived from the inner cell mass (ICM) of the embryo that have great potential for regenerative therapies because of their ability to self-renew and differentiate into almost all cell types. However, this developmental potential is influenced by the local cellular microenvironment, including cell surface bound ligands. In this study, we synthesized an artificial stem cell niche wherein vascular endothelial growth factor A (VEGFA) was functionally immobilized in an agarose hydrogel. Immobilized VEGFA treatments were able to upregulate mesodermal markers, brachyury and VEGF receptor 2, by day 4 and were CD34+CD41+ by day seven. Subsequently, VEGFA immobilized treatments were able to generate colony forming cells by day fourteen. This work demonstrates our ability to use functionalized hydrogels to guide ESCs toward blood progenitor cells and serves as a useful tool to replicate aspects of the embryonic microenvironment.

Non-competitive adsorption of polycyclic aromatic hydrocarbons (PAHs) from water onto activated carbon was studied alongside the performance of CO2-activated petroleum coke as a low-cost adsorbent. PAH adsorption was a two-stage process: a short, fast initial period followed by a long, slow period corresponding to the intra-particle diffusion of PAH molecules in macropores and micropores. The adsorption capacity was determined by total surface area accessible to PAH and the availability of active surface chemical groups. The positive dependence of adsorption capacity on surface oxygen groups and temperature was observed, suggesting a chemical nature of PAH adsorption. The interaction between PAH-activated carbon was however, weak and energetically similar to that of hydrogen bonds. Overall, PAH adsorption was an exothermic process that combined physisorption and chemisorption. CO2-activated petroleum coke had a greater SSA-normalized capacity than coal-derived commercial activated carbon (0.26 vs. 0.19 mg/m2). The capacity was significantly increased by post-oxidation to 0.62 mg/m2.

Embryonic stem cells (ESCs) are derived from the inner cell mass (ICM) of the embryo that have great potential for regenerative therapies because of their ability to self-renew and differentiate into almost all cell types. However, this developmental potential is influenced by the local cellular microenvironment, including cell surface bound ligands. In this study, we synthesized an artificial stem cell niche wherein vascular endothelial growth factor A (VEGFA) was functionally immobilized in an agarose hydrogel. Immobilized VEGFA treatments were able to upregulate mesodermal markers, brachyury and VEGF receptor 2, by day 4 and were CD34+CD41+ by day seven. Subsequently, VEGFA immobilized treatments were able to generate colony forming cells by day fourteen. This work demonstrates our ability to use functionalized hydrogels to guide ESCs toward blood progenitor cells and serves as a useful tool to replicate aspects of the embryonic microenvironment.