Efficient electrochemical energy conversion technologies, such as fuel cells and water electrolyzers, require high current densities to lower the capital cost for large-scale commercialization but are often limited by mass transport. In this study, we demonstrated exceptional electrochemical performances in proton electrolyte membrane water electrolyzers (PEMWEs) creating micropatterned pore channels in the porous transport layer (MPC PTL) using a picosecond laser. This approach yielded an impressive performance of 1.82 V @ 2 A·cm-2, which is better than commercial PTL of 1.90 V @ 2 A cm-2. The significant performance enhancement is attributed to the micropatterned porous channel structure, facilitating the efficient expulsion of oxygen bubbles and input of reactant water. This work provides valuable insights for the design of PTL responsible for biphasic transport in electrochemical energy conversion technologies.

Drug delivery through electroporation could be highly beneficial for the treatment of different types of diseased tissues within the human body. In this work, a mathematical model of reversible tissue electroporation is presented for injecting drug into the diseased cells. The model emphasizes the tissue boundary where the drug is injected as a point source. In addition, the effect of drug loss at tissue boundaries through extracellular space is studied elaborately. Multiple pulses are applied to deliver a sufficient amount of drug into the targeted cells. The set of differential equations that model the physical circumstances are solved numerically. This model obtains a mass transfer coefficient (MTC), in terms of pore fraction coefficient and drug permeability that controls the drug transport from extracellular to intracellular space. The drug penetration throughout the tissue is captured for the application of different pulses. The boundary effects on drug concentration are highlighted in this study. The advocated model is able to perform homogeneous drug transport into the cells so that the affected tissue is treated completely. This model can be applied to optimize clinical experiments by avoiding the lengthy and costly in vivo and in vitro experiments.

The nearshore zone turns out to be the area with the higher concentration of plastic debris and, for this reason, it is important to know the processes that affect the transport and the fate of this type of litter. This study focuses on investigating the dynamics of various plastic types under several hydrodynamic conditions primarily induced by waves. 2D tests were carried out at the Hydraulic Laboratory of the University of Messina reproducing the main phenomena that occurred during the wave propagation on a planar beach. More than 200 different conditions were tested changing the wave characteristics, the water depth, the plastic debris characteristics (density and shape), and the roughness of the fixed bottom. In general, it can be observed that the reduction in particle displacement occurs due to: i) a decrease in wave steepness; ii) an increase in depth; iii) an increase in particle size; iv) an increase in plastic density. However, the experimental investigation shows that some plastic characteristics and bed roughness, even when hydraulically smooth, can alter these results. The experimental data analysis identified a criterion for predicting the short-term fate of plastic debris under wave action. This criterion to determine equilibrium conditions, based on an empirical relationship, takes into account the wave characteristics, the bed roughness and slope, and the weight of the debris.

The hypothesis of the study was that (1) 3D printed drug delivery systems (DDS) could be characterized in situ during drug release using NMR/MRI techniques in terms of mass transport phenomena description (interfacial phenomena), particularly for systems dealing with two mobile phases (e.g., water and low molecular weight liquid polymer); (2) consequently, it could be possible to deduce how these interfacial mass transport phenomena influence functional properties of 3D printed DDS. Matrix drug delivery systems, prepared using masked stereolithography (MSLA), containing poly(ethylene glycol) diacrylate (PEGDA) and low molecular weight polyethylene glycol (PEG) with ropinirole hydrochloride (RH) were studied as example formulations. The PEGDA to PEG (mobile phase) concentration ratio influenced drug release. It was reflected in spatiotemporal changes in parametric T2 relaxation time (T2) and amplitude (A) images obtained using magnetic resonance imaging (MRI) and T1-T2 relaxation time correlations obtained using low-field time-domain nuclear magnetic resonance (LF TD NMR) relaxometry during incubation in water. For most of the tested formulations, two signal components related to PEG and water were assessed in the hydrated matrices by MRI relaxometry (parametric T2/A images). The PEG component faded out due to outward PEG diffusion and was gradually replaced by the water component. Both components spatially and temporally changed their parameters, reflecting evolving water-polymer interactions. The study shows that dynamic phenomena related to bidirectional mass transport can be quantified in situ using NMR and MRI techniques to gain insight into drug release mechanisms from 3D printed DDS systems.

The mechanics of capillary force in biological systems have critical roles in the formation of the intra- and inter-cellular structures, which may mediate the organization, morphogenesis, and homeostasis of biomolecular condensates. Current techniques may not allow direct and precise measurements of the capillary forces at the intra- and inter-cellular scales. By preserving liquid droplets at the liquid-liquid interface, we have discovered and studied ideal models, i.e., interfacial liquids and marbles, for understanding general capillary mechanics that existed in liquid-in-liquid systems, e.g., biomolecular condensates. The unexpectedly long coalescence time of the interfacial liquids revealed that the Stokes equation does not hold as the radius of the liquid bridge approaches zero, evidencing the existence of a third inertially limited viscous regime. Moreover, liquid transport from a liquid droplet to a liquid reservoir can be prohibited by coating the droplet surface with hydrophobic or amphiphilic particles, forming interfacial liquid marbles. Unique characteristics, including high stability, transparency, gas permeability, and self-assembly, are observed for the interfacial liquid marbles. Phase transition and separation induced by the formation of nanostructured materials can be directly observed within the interfacial liquid marbles without the need for surfactants and agitation, making them useful tools to research the interfacial mechanics.

The interpretation of mechanisms governing hot carrier reactivity on metallic nanostructures is critical, yet elusive, for advancing plasmonic photocatalysis. In this work, we explored the influence of the diffusion of molecules on the hot carrier extraction rate at the solid-liquid interface, which is of fundamental interest for increasing the efficiency of photodevices. Through a spatially defined scanning photoelectrochemical microscopy investigation, we identified a diffusion-controlled regime hindering the plasmon-driven photochemical activity of metallic nanostructures. Using low-power monochromatic illumination (<2 W cm-2), we unveiled the hidden influence of mass transport on the quantum efficiency of plasmonic photocatalysts. The availability of molecules at the solid-liquid interface directly limits the extraction of hot holes, according to their nature and energy, at the reactive spots in Au nanoislands on an ultrathin TiO2 substrate. An intriguing question arises: does the mass transport enhancement caused by thermal effects unlock the reactivity of nonthermal carriers under steady state?

The integration of metal-organic frameworks (MOFs) into composite systems serves as an effective strategy to increase the processability of these materials. Notably, MOF/fiber composites have shown much promise as protective equipment for the capture and remediation of chemical warfare agents. However, the practical application of these composites requires an understanding of their mass transport properties, as both mass transfer resistance at the surface and diffusion within the materials can impact the efficacy of these materials. In this work, we synthesized composite fibers of MOF-808 and amidoxime-functionalized polymers of intrinsic microporosity (PIM-1-AX) and measured the adsorption and mass transport behavior of n-hexane and 2-chloroethyl ethyl sulfide (CEES), a sulfur mustard simulant. We developed a new Fickian diffusion model for cylindrical shapes to fit the dynamic adsorption data obtained from a commercial volumetric adsorption apparatus and found that mass transport behavior in composite fibers closely resembled that in the pure PIM fibers, regardless of MOF loading. Moreover, we found that n-hexane adsorption mirrors that of CEES, indicating that it could be used as a structural mimic for future adsorption studies of the sulfur mustard simulant. These preliminary insights and the new model introduced in this work lay the groundwork for the design of next-generation composite materials for practical applications.

Surface barriers are commonly observed in nanoporous materials. Although researchers have explored methods to repair defects or create flawless crystals to mitigate surface barriers, these approaches may not always be practical or readily achievable in targeted metal-organic frameworks (MOFs). In our study, we propose an alternative approach focusing on the introduction of diverse ligands onto a MOF-808 node to finely adjust its adsorption and mass transport characteristics. Significantly, our findings indicate that while adsorption curves can be inferred based on the MOF\'s chemical composition and the probing molecule, surface permeabilities exhibit variations dependent on the specific probe utilized and the incorporated ligand. Our investigation, considering van der Waals forces exclusively between the adsorbate (e.g., n-hexane, propane, and benzene) and the adsorbent, revealed that augmenting these interactions can indeed improve surface permeation to a certain extent. Conversely, strong adsorption resulting from hydrogen bonding interactions, particularly with water in modified MOFs, led to compromised permeation within the MOF crystals. These outcomes provide valuable insights for the porous materials community and offer guidance in the development of adsorbents with enhanced affinity and superior mass transport properties for gases and vapors.

In this chapter, we present the design and fabrication of a device and implementation of a protocol to realize increased efficiency of immunoassays within microtiter plates. The device, WellProbe, is a 3D-structured probe that can be used to deliver precise flows at the bottom of standard well plates to establish concentric areas of shear stress intensities using hydrodynamically confined flows. The protocols involve both operation and data analysis.

A modified Metal-Organic Framework UiO-66-NH2-based photocathode in a zero-gap gas phase photoelectrolyzer was applied for CO2 reduction. Four types of porous carbon fiber layers with different wettability were employed to tailor the local environment of the cathodic surface reactions, optimizing activity and selectivity towards formate, methanol, and ethanol. Results are explained by mass transport through the different type and arrangement of carbon fiber support layers in the photocathodes and the resulting local environment at the UiO-66-NH2 catalyst. The highest energy-to-fuel conversion efficiency of 1.06 % towards hydrocarbons was achieved with the most hydrophobic carbon fiber (H23C2). The results are a step further in understanding how the design and composition of the photoelectrodes in photoelectrochemical electrolyzers can impact the CO2 reduction efficiency and selectivity.