Chloride Selective Membranes in Outflow Geometries for Water Treatment and Power Generation

Clean power generation and global water scarcity are two intertwined challenges that have become increasingly critical in our modern world. With the growth of population, the expansion of industrialization, and the disruption of traditional weather patterns, demand for energy and freshwater has surged. As a result, the world has turned its attention to innovative sustainable energy sources, offering a reliable and eco-friendly solution to our growing energy needs while protecting the environment from negative impacts associated with conventional energy generation methods.The electrochemical cell explored in this study holds significant promise in three separate domains, with each domain playing a crucial role in tackling demanding global challenges. This cell demonstrates applicability in desalination, separation processes, and power generation. The cell relies on the use of regenerable porous silver electrodes, which have the ability to selectively attract chloride ions through an electrochemical reaction involving silver and chloride. Symmetric silver/ silver chloride porous electrodes are employed to alternatively capture Cl− ions. The silver anode is oxidized and reacts with Cl− ions from the solution to form insoluble AgCl. Simultaneously, the silver cathode releases Cl− ions. The distinctive feature here is the new geometry, allowing the inlet flow to extend outward through the porous electrodes. This feature minimizes the energy consumption of the process by alleviating concentration polarization through advection. Concentration polarization is one of the main contributors to energy loss in electrochemical processes. Chapter one thoroughly explores strategies and technologies targeted at addressing environmental challenges, with a primary focus on desalination, separation, and power generation. The chapter emphasizes electrochemical methods as sustainable and efficient solutions for overcoming the environmental challenges Additionally, it introduces the electrochemical cell utilized in this study and outlines its role in addressing these environmental challenges. In chapter two, our focus is entirely on the field of desalination. Desalination plays a pivotal role in addressing water scarcity, especially in regions with limited or contaminated freshwater sources. We delve into the growing application of electrochemical desalination methods. Our exploration of this system's behavior encompasses the use of steady-state analytical models, transient numerical models, and practical experimentation. Our analysis of desalination performance involves an assessment of the degree of separation attained, the system's throughput capacity, its charge efficiency, and its energy consumption [1]. In the third chapter, the system is harnessed for specific ion separation, capitalizing on the chemical selectivity of its electrodes. These capabilities for selective separation also prove to be a valuable asset for tackling urgent environmental issues in industries like food processing, leather production, and petroleum refineries. This chapter reports results of experiments to separate chloride ions from other anions present in solutions representative of industrial and agricultural wastewater. Chapter 4 introduces a shift in the electrochemical cell's role, transitioning from desalination to power generation. This transformation is based on the cell's capability to harness energy arising from the difference in salt concentration between saltwater and freshwater, thereby introducing a renewable energy source. The analysis of power generation performance in this chapter relies on the use of steady-state analytical models. It involves a comprehensive exploration of the cell's behavior across a range of parameters. This examination encompasses the impact of different velocities, variations in inlet concentration differences, adjustments in electrode spacing, and diverse current levels. We believe that there is a need for further research to optimize the utilization of the electrochemical cell across various applications, as will be discussed in chapter 5. Collectively, our study emphasizes the potential of this electrochemical cell to serve as a bridge connecting the domains of desalination, selective separation, and power generation to address global challenges with issues such as water scarcity, the demand for sustainable energy sources, and environmental conservation

New Approaches to Study Thymic Seeding & Regeneration

Hematopoietic Cell Transplantation (HCT) is a common treatment for patients suffering from a variety of malignant or benign diseases, reconstituting the hematopoietic system after preconditioning treatment. In patients undergoing HCT, the capacity of the thymus to produce functional T cells is inhibited due to damage from cytotoxic preconditioning. Endogenous thymus regeneration depends on the complex relationship between thymus stromal cells (including vascular endothelial cells (EC)) and the recruitment of de novo “seeding” early thymic progenitors (ETPs) from the regenerated bone marrow (BM). However; functional damage to the vascular network (ECs compartment) may alter the hemodynamics and negatively impact ETP homing and thymus regeneration. Traditionally, flow cytometry, immunohistochemistry, ex vivo imaging, and other molecular biology techniques have been applied to study the thymus in preclinical mouse models since direct visualization of the native thymus in live mice was deemed impossible. In my project, we developed a new method for intravital two-photon microscopy of the native thymus to study functional changes to the vascular system after cytotoxic preconditioning. We hypothesize that cytotoxic preconditioning causes functional and anatomical changes in blood vessel architecture, especially cortical vasculature, that negatively impacts ETP homing and leads to long-term changes in the thymus microenvironment. Using our methodology, we were able to quantify the changes to the blood vessel network after sublethal irradiation (4.5 Gy). We were able to quantify blood flow velocity and shear rate in cortical blood vessels and identified a subtle but significant increase in vessel diameter and barrier function ~24 hrs post-sublethal irradiation. We validated this result using tissue clearing and ex vivo imaging. In addition, most cortical blood velocity is <500 μm/s in both control and one day after sublethal irradiation, although no significant changes were observed in blood velocity and shear rate between the groups at this time point. Taken together, our study suggests that native intravital thymus imaging is a powerful technique enabling functional and anatomical characterization of the thymus vascular network. We believe further work will help clarify the changes to the vascular system at later time points and in the context of higher irradiation doses. This method enables a whole new paradigm for studying thymus biology not previously possible. In the second project, we developed whole organ imaging based on a modified tissue clearing method and investigated the performance based on clearing capability, fluorescence preservation, imaging depth, and size deformation. An optical clearing technique is a powerful tool to reduce light scattering for deep-tissue imaging and enable 3-D imaging of thick tissue samples. We hypothesize that by modifying the temperature and pH of the ultimate 3D imaging of solvent-cleared organs (uDISCO) clearing method, we can improve the retention of GFP fluorescence over time without sacrificing the clearing capability. We developed a modified uDISCO clearing method named a-ucDISCO (alkaline-ultimate chilled DISCO) by adjusting the PH and temperature and performed ex vivo imaging of vascular networks of the murine thymus using two-photon microscopy. Our results revealed a significant increase in GFP fluorescence retention over time compared to the standard uDISCO method. This modified clearing method, therefore, represents an alternative approach for three-dimensional whole-organ imaging of samples with endogenous GFP fluorescence

Techno-economic feasibility analysis of an extreme heat flux micro-cooler

Summary: An estimated 70% of the electricity in the United States currently passes through power conversion electronics, and this percentage is projected to increase eventually to up to 100%. At a global scale, wide adoption of highly efficient power electronics technologies is thus anticipated to have a major impact on worldwide energy consumption. As described in this perspective, for power conversion, outstanding thermal management for semiconductor devices is one key to unlocking this potentially massive energy savings. Integrated microscale cooling has been positively identified for such thermal management of future high-heat-flux, i.e., 1 kW/cm2, wide-bandgap (WBG) semiconductor devices. In this work, we connect this advanced cooling approach to the energy impact of using WBG devices and further present a techno-economic analysis to clarify the projected status of performance, manufacturing approaches, fabrication costs, and remaining barriers to the adoption of such cooling technology

Live-animal imaging of native haematopoietic stem and progenitor cells.

The biology of haematopoietic stem cells (HSCs) has predominantly been studied under transplantation conditions1,2. It has been particularly challenging to study dynamic HSC behaviour, given that the visualization of HSCs in the native niche in live animals has not, to our knowledge, been achieved. Here we describe a dual genetic strategy in mice that restricts reporter labelling to a subset of the most quiescent long-term HSCs (LT-HSCs) and that is compatible with current intravital imaging approaches in the calvarial bone marrow3-5. We show that this subset of LT-HSCs resides close to both sinusoidal blood vessels and the endosteal surface. By contrast, multipotent progenitor cells (MPPs) show greater variation in distance from the endosteum and are more likely to be associated with transition zone vessels. LT-HSCs are not found in bone marrow niches with the deepest hypoxia and instead are found in hypoxic environments similar to those of MPPs. In vivo time-lapse imaging revealed that LT-HSCs at steady-state show limited motility. Activated LT-HSCs show heterogeneous responses, with some cells becoming highly motile and a fraction of HSCs expanding clonally within spatially restricted domains. These domains have defined characteristics, as HSC expansion is found almost exclusively in a subset of bone marrow cavities with bone-remodelling activity. By contrast, cavities with low bone-resorbing activity do not harbour expanding HSCs. These findings point to previously unknown heterogeneity within the bone marrow microenvironment, imposed by the stages of bone turnover. Our approach enables the direct visualization of HSC behaviours and dissection of heterogeneity in HSC niches

The Axolotl Limb Regeneration Model as a Discovery Tool for Engineering the Stem Cell Niche

Purpose of reviewRecent advances in genomics and gene editing have expanded the range of model organisms to include those with interesting biological capabilities such as regeneration. Among these are the classic models of regeneration biology, the salamander. Although stimulating endogenous regeneration in humans likely is many years away, with advances in stem cell biology and biomedical engineering (e.g. bio-inspired materials), it is evident that there is great potential to enhance regenerative outcomes by approaching the problem from an engineering perspective. The question at this point is what do we need to engineer?Recent findingsThe value of regeneration models is that they show us how regeneration works, which then can guide efforts to mimic these developmental processes therapeutically. Among these models, the Accessory Limb Model (ALM) was developed in the axolotl as a gain-of-function assay for the sequential steps that are required for successful regeneration. To date, this model has identified a number of proregenerative signals, including growth factor signaling associated with nerves, and signals associated with the extracellular matrix (ECM) that induce pattern formation.SummaryIdentification of these signals through the use of models in highly regenerative vertebrates (e.g. the axolotl) offers a wide range of possible modifications for engineering bio-inspired, biomimetic materials to create a dynamic stem cell niche for regeneration and scar-free repair