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Thanks to advances in chemical synthesis that enable control over the size, structure, properties, and functionalization, magnetic nanoparticles (NPs) present unique opportunities in areas as diver...

Experimental and numerical investigations are performed to evaluate the mass diffusion in Agave Americana natural fiber composites considering several environmental conditions. The effect of fiber pretreatment by alkaline hornification is analyzed on the moisture uptake behavior of the Agave fiber composites. It was observed that water retention value, which is a measure of affinity towards moisture, reduces with each subsequent hornification cycle. The microstructural investigations were performed to analyze the morphological changes in fiber microfibrils. Composite specimens were subjected to accelerated ageing under water and humidity conditions at controlled temperatures between 0 °C and 75 °C. Composites were weighted periodically and mass gain curves were analyzed. A comparison is drawn between the mass gain behavior of composites fabricated using untreated and alkali hornified Agave fibers. The studies have revealed a clear influence of alkaline hornification on the improvement of the hydrothermal durability of the Agave fibers. The effective moisture diffusivity of the composites is determined using edge correction factors for rectanguloid specimens. Finally, the experimental mass gain is compared with the numerical Fick’s law based finite element (FE) approximations.

Li-ion batteries (LIB) are ubiquitous in today’s world with applications ranging from portable electronic devices to electric vehicles. These set of applications require the batteries to have diverse energy and power dense configurations. For these reasons the LIB exists in multiple form factors such as cylindrical, pouch cell configurations and different chemistries. The most commercialized and successful LIB are based on intercalation mechanism, which requires shuttling of Li-ion between anode and cathode with redox reaction occurring on the surface of the electrodes and ultimately leading to the Li-ions to diffuse into the host structure of the electrode. Such electrodes are naturally made to be porous, to maximize the surface area for redox and electrochemical reaction, also giving rise to multiple pathways for Li-ion diffusion and migration. These electrode structures are also integrated with additives to increase the electronic conductivity and mechanical strength. This gives rise to the microstructure as a matrix of different phases with multi-length scale structure and characteristics at different scales. The performance and operation of battery is closely intertwined with these electrode microstructure, and thus microstructural characteristics significantly influence the transport process or kinetics of the reaction. This relation between performance and electrode microstructure is not limited to the composition of electrode rather even with fixed chemical composition the widely different structural arrangement of the phases alters the short- and long-range interactions within the electrode. Specifically based on electrochemical performance model, the electrochemical-thermal interactions can be captured with few important effective electrode properties such as interfacial area, tortuosity and conductivity. Here we develop a framework for the accurate prediction of these effective electrode properties as a function of the microstructural properties. For this purpose of effective electrode property prediction, we develop an integrated framework, including information from the physics informed mesoscale model along with the data driven models. The accurate effective electrode properties are evaluated from pore-scale characterization of microstructure, to serve as output for data set. Our main objective with developing such a framework is to describe the effective electrode properties with simple yet meaningful correlations, which can accurately capture physics while maintaining high predictive accuracy, thus also providing directions for better electrode manufacturing.

In the United States many women in science, technology, engineering, and mathematics (STEM) leave their careers after becoming a parent. Attrition is simultaneously occurring with workforce shortages in STEM with two million jobs potentially unfilled by 2025. While there has been an increase in STEM recruitment of women over recent decades, policies aimed at decreasing departure of women in STEM have not been prioritized. The Family and Medical Leave Act of 1993 (FMLA) guarantees workers up to 12 weeks of unpaid, job-protected leave, but has not shown to increase workforce attachment of new mothers. Instead, studies suggest that short durations of paid leave (6-12 weeks) increase workforce attachment. Medical consensus suggests that a leave of 26 weeks is necessary for maternal health and a leave of 40 weeks is optimal for infant well-being. Coupled with recently introduced paid parental leave legislation in Congress, we recommend timely action to decrease the departure of women from the workforce and to strengthen gender equality in STEM. We recommend instituting 12 weeks of federal paid family leave (PFL) under the recently introduced national family leave insurance program in the Family and Medical Insurance Leave Act (FAMILY Act; S. 463/H.R. 1185).

Three-dimensional (3D) deterministic design of electrodes could enable simultaneous high energy and power density for electrochemical energy storage devices. The goal of such electrode architectures is to provide adequate charge (electron and ion) transport pathways for high power while maintaining high active material loading (> 10 mg cm-2) for high areal and volumetric capacity. However, it remains a challenge to fabricate such electrodes with processes that are both scalable and reproducible. Towards this end, I will discuss how the fabrication of such an electrode is made possible by combining highly tunable, free-standing, and aligned CNT foams with aqueous electrodeposition of a model intercalation-type transition metal oxide, MoO3. Morphological characterization including X-ray micro computed tomography indicate that the obtained composite is highly homogenous. Electrodes with active mass loading up to 18 mg cm-2 can reach near-theoretical Li-ion intercalation capacities within 1.7 hours. The highest mass loading electrodes also led to areal and volumetric capacities of 4.5 mAh cm-2 and 290 mAh cm-3 with 55% capacity retention for charge/discharge times of 10 minutes. I will also describe the use of mesoscale modeling to understand and ultimately, predict the performance of this electrode architecture. Overall, our work demonstrates a scalable, deterministic 3D electrode design strategy using electrodeposition and free-standing, aligned CNT foams that lead to high areal and volumetric capacities and good rate performance due to well-distributed charge transport pathways.