Transport Studies Research Articles

Bright and Fast Emission from Robust Supramolecular J-Aggregate Nanostructures through Silica-Encapsulation.

We introduce a two-step silica-encapsulation procedure to optimize both the optical efficiency and structural robustness of 5,5',6,6'-tetrachloro-1,1'-diethyl-3,3'-di(4-sulfobutyl)-benzimidazolocarbocyanine (TDBC), a two-dimensional sheet-like J-aggregate. We report a fluorescence quantum yield of ∼98%, the highest quantum yield recorded for any J-aggregate structure at room temperature, and a fast, emissive lifetime of 234 ps. Silica, as an encapsulating matrix, provides optical transparency, chemical inertness, and robustness to dilution, while rigidifying the J-aggregate structure. Our in situ encapsulation process preserves the excitonic structure in TDBC J-aggregates, maintaining their light absorption and emission properties. The homogeneous silica coating has an average thickness of 0.5-1 nm around J-aggregate sheets. Silica encapsulation permits extensive dilutions of J-aggregates without significant disintegration into monomers. The narrow absorbance and emission line widths exhibit further narrowing upon cooling to 79 K, which is consistent with J-type coupling in the encapsulated aggregates. This silica TDBC J-aggregate construct signifies (1) a bright, fast, and robust fluorophore system, (2) a platform for further manipulation of J-aggregates as building blocks for integration with other optical materials and structures, and (3) a system for fundamental studies of exciton delocalization, transport, and emission dynamics within a rigid matrix.

Investigation of numerical transport models in protein-based molecular junctions with cofactors of diverse chemical natures

The cofactors of proteins dictate the charge transport mechanism across molecular junctions when self-assembled protein monolayers are sandwiched between two metal electrodes. Here, we summarized how the chemical coordination nature of cofactors in various proteins modulates electrical conductance by investigating electronic transport studies across different protein-based molecular junctions under various forces applied under the AFM tip. We have utilized several numerical techniques of electronic transport to analyse the experimentally obtained current–voltage measurements across various protein-based molecular junctions and depicted the origin of electronic modulation in the electrical conductance under different external stimuli. We could also find the origin of electronic conductance modulation under external stimuli at various applied forces by obtaining several analytical transport parameters such as energy barrier, coupling strength, and electrical conductance values. Utilizing density-functional-theory calculations, we further validate that the electronic density of states present in the cofactors within the proteins dominates the electronic transport behaviours across protein-based molecular junctions. Our findings reveal the limiting factor for applying various external stimuli on different proteins, which could be further valuable in bioelectronic applications. We have also found that the organic cofactor containing protein follows all the tunneling mechanism-related numerical transport models and the electronic transport across proteins with pure inorganic cofactors follows Landauer transport formalism.

Microstructural study with enhanced dielectric and magnetic properties of Cu1-xCdxFe2O4 nanoparticles prepared at low-temperature green-synthesized technique

The green elaboration tool has taken much consideration due to its consistent and economical ways of producing pure and regular dispersed NPs. The preparation tool is a simple, environmentally friendly, and cost-effective method that does not use toxic chemicals. Therefore, the biological mechanisms themselves act as a reducing agent that prevents, on the surface of nanoparticles, the adsorption of chemical agents. Therefore, we focus in this work on the bio-synthesizes and the characterization (crystallographic, magnetic, transport, and dielectric study) of Cu1-xCdxFe2O4(x = 0.0, 0.3 and x = 0.5) spinel ferrites. X-ray diffraction, transmission electron microscopy (TEM), and photoelectron spectroscopy (XRD and XPS) have been employed to study crystallographic characteristics and chemical bond formation. Surface parameters analysis was conducted using BET isotherms and validated the decreases in specific surface area in the substitution sample. The electrical investigation proves the semiconductor behavior, and the thermal activation are dominated by the small polaron hopping mechanism in the nano-ferrites Cu1-xCdxFe2O4. In addition, the prepared NPS exhibits low dielectric losses. Using the ZFC-FC and M(H) measurement techniques, important modifications in the magnetic behaviors have been detected in the elaborated nanoparticles. Accordingly, the substitution of Cu1-xCdxFe2O4 leads to transitions from ferromagnetic to superparamagnetic behaviors, the increase of the magnetic saturation, and decreased magnetic anisotropy has been shown in Cu0·7Cd0·3Fe2O4 spinel structure.

Routes with roots: Pedestrian route choices and sense of place of an urban university community

Understanding how people choose routes in urban environments is essential for effective urban planning. While conventional transportation studies focus on utilitarian decision-making, this research investigates the complex interplay between human-environment interactions and emotional attachments to places, which influence transportation choices. Specifically, we examine the impact of sense of place in pedestrian route choice within a densely populated urban university community. Unlike typical urban settings characterized by clear roads and landmarks, university environments often feature intricate layouts with diffuse pathways, shared spaces, and a lack of clear spatial hierarchies. This complexity challenges conventional spatial knowledge acquisition methods. Individuals navigating such environments tend to rely on socio-sensory wayfinding strategies, developing emotional connections to specific places and routes over time. Consequently, route choices in these contexts may not always be deliberate but rather subconscious and nuanced. Our study focuses on elucidating the impact of the sense of place—a composite of conscious and subconscious perceptions, emotions, and attachments to a location—on daily route decisions. Through structural equation modeling (SEM) analysis, we demonstrate that the sense of place significantly influences route choices within community building complexes, surpassing utilitarian considerations as a primary explanatory factor. These findings underscore the importance of emotional and psychological factors in shaping urban route decisions, offering valuable insights for urban planning and management strategies.

The importance of long range Fe–Fe interactions in magnetically ordered 2D Fe0.2Ni0.8/Ni(001) and Fe0.3Ni0.7/Ni(001) alloy systems

We develop a theoretical approach to study the magnonic properties of the 2D ordered surface Fe–Ni alloys with 20% and 30% Fe on a face-centered cubic Ni(001) surface substrate. The surface alloy nanostructures in stable equilibrium are determined by computing the lowest energy configurations of constitutive supercells of the ordered alloys. The magnetic exchange constants of the ground state of the stable systems are calculated to define their Heisenberg Hamiltonians using the DFT Spin-Polarized Relativistic Korringa–Kohn–Rostoker (SPRKKR) method and considering Fe–Fe interactions up to third nearest neighbors. To determine the propagating exchange spin-wave modes, evanescent modes, and the consequent magnonic properties, the spin dynamics of the magnetic surface alloy nanostructures are solved using the phase field matching theory (PFMT). Our results indicate that the Fe–Fe exchange interactions up to third nearest neighbors are vital for accurately describing their magnonics. In particular, the exchange interactions influence the form of dispersion branches for the high-energy spin-wave modes of the Fe–Ni surface alloys considered. Appropriate Green’s functions are also derived from the PFMT method to compute the local densities of states (LDOS) for the atomic sites at the surface boundary. For the case of 20% Fe surface alloy, the Fe–Fe exchange interactions shift the Fe LDOS peaks to lower frequency intervals. We also distinguish the emergence of remarkable LDOS peaks for the he case of the 30% Fe surface alloy at specific Ni sites. These peaks change positions under second and third nearest neighbor Fe–Fe interactions, heralding new accessible spin-wave channels. Our results contribute to establishing a systematic understanding of the magnonics of the magnetic surface alloys of transition metal (TM) materials. This new knowledge will enable the study of the quantum transport of spin waves at interfacial alloy nanojunctions composed of such materials. The present DFT-PFMT theoretical approach is general and can be applied to other surface TM alloy magnetic nanostructures.

Utilization of emergency medical services by Culturally and Linguistically Diverse patients: a population-based retrospective study

ABSTRACT Objectives: To compare emergency medical services (EMS) utilization between culturally and linguistically diverse (CALD) and non-CALD patients in Victoria, Australia. Methods: A retrospective study of EMS attendances and transports in Victoria from January 2015 to June 2019, utilising linked EMS, hospital emergency and admissions data. The CALD and non-CALD patients who received EMS care and transport to a Victorian public emergency department were included. The incidence of EMS use for CALD and non-CALD patients based on the 2016 Census population and expressed per 100,000 person-years. Results: In 1,261,167 included patients, there were 272,100 (21.6%) CALD and 989,067 (78.4%) non-CALD patients. Before adjustment for age and sex, EMS utilization for CALD patients was 13% lower than non-CALD patients (incidence rate ratio [IRR] 0.87, 95% CI: 0.87-0.87). When stratified by age groups, CALD patients aged under 70 years had significantly lower rates of EMS utilization than non-CALD patients, while CALD patients aged 75 years or older were more likely than non-CALD patients to use EMS (IRR 1.08, 95% CI: 1.07-1.09). The CALD patients were less likely to utilize EMS for trauma/external injury (IRR = 0.67, 95% CI: 0.66-0.68) and mental health/alcohol/drug problems (IRR = 0.39, 95% CI: 0.38-0.40). After adjustment for differences in the age and sex distribution of CALD and non-CALD populations, CALD patients were 51% less likely to utilise EMS than non-CALD patients (IRR 0.49, 95% CI: 0.42-0.56). Conclusions: The CALD patients used EMS less frequently than non-CALD patients with significant variation observed across age groups, countries of birth, and clinical presentation. Further research is needed to understand the factors that may be contributing to these disparities.

Impurity transport study based on measurement of visible wavelength high-n charge exchange transitions at W7-X

A recently installed high-speed charge exchange diagnostic at the W7-X stellarator has been used to identify several high-n Rydberg emission lines near 500 nm following impurity injections. The wavelengths of observed high-n Rydberg transitions are independent of the impurity species and originate from ions with ionization states ranging from 14+ to 45+ suggesting that this approach can be applied to a variety of heavy impurities. Moreover, little to no passive signal is observed since the high-n energy levels are unlikely to be populated by electron impact excitation. The combination of the newly developed diagnostic and the observation of high-n Rydberg states provides spatially resolved, high-speed measurements of multiple charge states which are analyzed in a Bayesian inference framework to determine both impurity diffusion and convection profiles. Measurements from the 2023 experimental campaign conclusively show high diffusion and an inward pinch in the core, well above predictions by neoclassical theory.

Improving train services to increase student mobility and safety on the Purwakarta-Karawang route

Transportation is essential for the mobility of workers and students, yet many prefer motorcycles over public transportation like trains due to inadequate schedules and limited train availability. This choice contributes to Indonesia's high motorcycle usage and associated traffic accident risks. This study focuses on the Purwakarta-Karawang train route and its impact on student mobility at Universitas Singaperbangsa Karawang. Employing a qualitative method with descriptive data collection and SWOT analysis, this research gathers student feedback on current train schedules and their impact on daily commutes. Findings indicate that increasing the number of train schedules could significantly improve student mobility and reduce the reliance on motorcycles, thereby decreasing traffic accidents. Moreover, better train schedules could enhance access to educational and employment opportunities. The study suggests that the local government should consider expanding and optimizing train services to address these issues. This research contributes to the broader field of transportation studies by highlighting the importance of efficient public transport schedules in reducing traffic accidents and supporting student mobility. It emphasizes the need for policy adjustments to improve Indonesia's public transportation infrastructure and services by proposing practical solutions.

A numerical inquiry of the MHD radiative thin film nanofluid flow and heat transfer augmentation for Ni and Ta nanoparticles of different shapes dispersed in C 12 H 26–C 15 H 32 over an unsteady, curved stretching surface

Thin films are a versatile technology used in various industries, including light-emitting diodes, magnetic recording media, electronic device manufacturing, and optical coating. They are crucial for studying quantum phenomena, superlattices, and multiferroic materials. Their small size allows for better thermal transport studies due to the combination of thin film flow and nanoparticles. Therefore, this study aims to investigate thin film flow and heat transfer with the effects of thermal radiations, magnetic field, and velocity slip in association with tantalum ( Ta ) and nickel ( Ni ) nanoparticles that emerged in kerosene oil ( C 12 H 26 − C 15 H 32 ) toward a curved stretching surface. A review of the pertinent literature indicates that no research has previously been done on the present problem of an unsteady thin film flow across a curved stretching surface. The problem under consideration is modeled by choosing the curvilinear coordinate system. The controlling nonlinear system of partial differential equations is transformed into the system of ordinary differential equations by using an appropriate similarity transformation and then solved numerically using the BVP 4 C technique in MATLAB . The impact of significant physical parameters on velocity, temperature, skin friction, and Nusselt numbers are depicted through graphs and radar charts. The investigation highlights the significant influence of magnetohydrodynamics ( MHD ) , thermal radiation, volumetric fraction, and velocity slip on the enhancement of nanofluid temperature. It is also noted that cylindrical-shaped Ta nanoparticles exhibited the maximum velocity, while blade-shaped Ni nanoparticles showed the lowest. Moreover, the maximum and minimum temperatures were observed for blade-shaped Ni nanoparticles and cylindrical Ta nanoparticles, respectively. Additionally, the maximum and minimum values of skin friction are found for cylindrical Ni nanoparticles and blade-shaped Ta nanoparticles, respectively. Similarly, the maximum and minimum Nusselt numbers are recorded for cylindrical Ta nanoparticles and blade-shaped Ni nanoparticles, respectively.

Kinesin-1-transported liposomes prefer to go straight in 3D microtubule intersections by a mechanism shared by other molecular motors

Kinesin-1 ensembles maneuver vesicular cargoes through the three-dimensional (3D) intracellular microtubule (MT) network. To define how such cargoes navigate MT intersections, we first determined how many kinesins from an ensemble on a lipid-based cargo simultaneously engage a MT, and then determined the directional outcomes (straight, turn, terminate) for liposome cargoes at perpendicular MT intersections. Run lengths of 350-nm diameter liposomes decorated with up to 20, constitutively active, truncated kinesin-1 KIF5B (K543) were longer than single motor transported cargo, suggesting multiple motor engagement. However, detachment forces of lipid-coated beads with ~20 kinesins, measured using an optical trap, showed no more than three simultaneously engaged motors, with a single engaged kinesin predominating, indicating anticooperative MT binding. At two-dimensional (2D) and 3D in vitro MT intersections, liposomes frequently paused (~2 s), suggesting kinesins simultaneously bind both MTs and engage in a tug-of-war. Liposomes showed no directional outcome bias in 2D (1.1 straight:turn ratio) but preferentially went straight (1.8 straight:turn ratio) in 3D intersections. To explain these data, we developed a mathematical model of liposome transport incorporating the known mechanochemistry of kinesins, which diffuse on the liposome surface, and have stiff tails in both compression and extension that impact how motors engage the intersecting MTs. Our model predicts the ~3 engaged motor limit observed in the optical trap and the bias toward going straight in 3D intersections. The striking similarity of these results to our previous study of liposome transport by myosin Va suggests a "universal" mechanism by which cargoes navigate 3D intersections.

Bridging the gap between high-speed rail transport studies and cluster economics through social knowledge exchange: future research potential

ABSTRACT Within the high-speed rail debate (HSR) there has been lacking in-depth theoretical and evidential research on the role HSR has on tacit knowledge flows between industrial clusters or regions of economic productivity. The research that has begun to emerge has focused on knowledge indicators such as patents for social/tacit knowledge exchange, which this paper raises concerns over. This review aims to discover new links for HSR with cluster economics through social knowledge theory and aims to create a conceptual framework that will provide a new perspective for future research in the HSR debate concerning social knowledge exchange. Potential implications are presented for future transport policy decision-making, based on the relationship HSR may have with inter-regional tacit knowledge flows and accessibility benefits in regional balancing. Future research considerations are pointed out that argue to measure the flow of knowledge from HSR, research needs to go in-depth to the social aspect of interactions and relationship buildings, as quantitative data will struggle to capture tacit knowledge flow itself, due to the tacit nature of such information. The presented framework highlights the tacit nature of interactions facilitated by HSR connectivity.

Rational Construction of Two-Dimensional Conjugated Metal-Organic Frameworks (2D c-MOFs) for Electronics and Beyond.

ConspectusTwo-dimensional conjugated metal-organic frameworks (2D c-MOFs) have emerged as a novel class of multifunctional materials, attracting increasing attention due to their highly customizable chemistry yielding programmable and unprecedented structures and properties. In particular, over the past decade, the synergistic relationship between the conductivity and porosity of 2D c-MOFs has paved the way toward their widespread applications. Despite their promising potential, the majority of 2D c-MOFs have yet to achieve atomically precise crystal structures, hindering the full understanding and control over their electronic structure and intrinsic charge transport characteristics. When modulating the charge transport properties of two-dimensional layered framework materials, decoupling the charge transport processes within and in between layers is of paramount importance, yet it represents a significant challenge. Unfortunately, 2D c-MOFs systems developed so far have failed to address such a major research target, which can be achieved solely by manipulating charge transport properties in 2D c-MOFs. 2D c-MOFs offer a significant advantage over organic radical molecules and covalent organic frameworks: polymerization through oxidative coordination is a viable route to form "spin-concentrated assemblies". However, the role of these spin centers in charge transport processes is still poorly understood, and the intrinsic dynamics and properties of these spins have seldom been investigated. Consequently, overcoming these challenges is essential to unlock the full potential of 2D c-MOFs in electronics and other related fields, as a new type of quantum materials.In this Account, we summarize and discuss our group's efforts to achieve full control at the atomic level over the structure of 2D c-MOFs and their applications in electronics and spintronics, thereby providing distinct evidence on 2D c-MOFs as a promising platform for exploring novel quantum phenomena. First, we unravel the key role played by the rational design of the ligands to decrease the boundary defects, achieve atomically precise large single crystals, and investigate the intrinsic charge transport properties of 2D c-MOFs. The advantages and disadvantages of the current structural elucidation strategies will be discussed. Second, the fundamental challenge in 2D c-MOF charge transport studies is to decouple the in-plane and interlayer charge transport pathways and achieve precise tuning of the charge transport properties in 2D c-MOFs. To address this challenge, we propose a design concept for the second-generation conjugated ligands, termed "programmable conjugated ligands", to replace the current first-generation ligands which lack modifiability as they mainly consist of sp2 hybridization atoms. Our efforts also extend to controlling the spin dynamics properties of 2D c-MOFs as "spin concentrated assemblies" using a bottom-up strategy.We hope this Account provides enlightening fundamental insights and practical strategies to overcome the major challenges of 2D c-MOFs for electronics and spintronics. Through the rational design of structural modulation within the 2D plane and interlayer interactions, we are committed to making significant steps forward for boosting the functional complexity of this blooming family of materials, thereby opening clear perspectives toward their practical application in electronics with the ultimate goal of inspiring further development of 2D c-MOFs and unleashing their full potential as an emerging quantum material.

Synthesis, Characterization, and Potential Usefulness in Liver Function Assessment of Novel Bile Acid Derivatives with Near-Infrared Fluorescence (NIRBAD).

Conventional serum markers often fail to accurately detect cholestasis accompanying many liver diseases. Although elevation in serum bile acid (BA) levels sensitively reflects impaired hepatobiliary function, other factors altering BA pool size and enterohepatic circulation can affect these levels. To develop fluorescent probes for extracorporeal noninvasive hepatobiliary function assessment by real-time monitoring methods, 1,3-dipolar cycloaddition reactions were used to conjugate near-infrared (NIR) fluorochromes with azide-functionalized BA derivatives (BAD). The resulting compounds (NIRBADs) were chromatographically (FC and PTLC) purified (>95%) and characterized by fluorimetry, 1H NMR, and HRMS using ESI ionization coupled to quadrupole TOF mass analysis. Transport studies using CHO cells stably expressing the BA carrier NTCP were performed by flow cytometry. Extracorporeal fluorescence was detected in anesthetized rats by high-resolution imaging analysis. Three NIRBADs were synthesized by conjugating alkynocyanine 718 with cholic acid (CA) at the COOH group via an ester (NIRBAD-1) or amide (NIRBAD-3) spacer, or at the 3α-position by a triazole link (NIRBAD-2). NIRBADs were efficiently taken up by cells expressing NTCP, which was inhibited by taurocholic acid (TCA). Following i.v. administration of NIRBAD-3 to rats, liver uptake and consequent release of NIR fluorescence could be extracorporeally monitored. This transient organ-specific handling contrasted with the absence of release to the intestine of alkynocyanine 718 and the lack of hepatotropism observed with other probes, such as indocyanine green. NIRBAD-3 administration did not alter serum biomarkers of hepatic and renal toxicity. NIRBADs can serve as probes to evaluate hepatobiliary function by noninvasive extracorporeal methods.

Congenital Heart Disease and Genetic Changes in Folate/Methionine Cycles

Congenital heart disease is one of the most common congenital malformations and thus represents a considerable public health burden. Hence, the identification of individuals and families with an increased genetic predisposition to congenital heart disease (CHD) and its possible prevention is important. Even though CHD is associated with the lack of folate during early pregnancy, the genetic background of folate and methionine metabolism perturbations and their influence on CHD risk is not clear. While some genes, such as those coding for cytosolic enzymes of folate/methionine cycles, have been extensively studied, genetic studies of folate transporters (de)glutamation enzymes and mitochondrial enzymes of the folate cycle are lacking. Among genes coding for cytoplasmic enzymes of the folate cycle, MTHFR, MTHFD1, MTR, and MTRR have the strongest association with CHD, while among genes for enzymes of the methionine cycle BHMT and BHMT2 are the most prominent. Among mitochondrial folate cycle enzymes, MTHFD2 plays the most important role in CHD formation, while FPGS was identified as important in the group of (de)glutamation enzymes. Among transporters, the strongest association with CHD was demonstrated for SLC19A1.

Quantized heat flow in graphene quantum Hall phases: Probing the topological order

Topological quantum numbers are often used to characterize the topological order of phase having protected gapless edge modes when the system is kept in a space with the boundary. The famous examples in this category are the quantized electrical Hall conductance and thermal Hall conductance, which encodes the topological order of integer and fractional quantum Hall states. Here, we review the recent thermal transport study of integer and fractional quantum Hall states realized in graphene-based van der Waals heterostructures.

Study of optoelectronic, transport, and mechanical aspects of lead-free double perovskites Rb2AgTlX6 (X = Cl, Br) for green energy applications

The double perovskites are emerging candidates for renewable energy applications. This work uses the extensive density functional theory (DFT) method to investigate the structural, optoelectronic, transport, and mechanical properties of Rb2AgTlX6 (X = Cl, Br). The thermal and structural stabilities of Rb2AgTlX6 (X = Cl, Br) are investigated through formation energy and tolerance factorevaluation.The Rb2AgTlCl6 and Rb2AgTlBr6 have direct band gaps of 1.61 eV and 1.08 eV. The reported band gap reduction is associated with the p-d hybridization of cations and anions. Investigating optical characteristics yields important insights via the dielectric constant ε(ω), refractive index n(ω), absorption α(ω), and reflectivity R(ω). The ability to absorb light in visible and ultraviolet spectra as demonstrated by optical characteristics highlights the potentialof Rb2AgTlX6 for solar cell technology. In addition, the significant electrical conductivity and Seebeck coefficient led to a notable reduction in heat conductivity and figure of merit values of 0.68 and 0.67 at higher temperatures. Elastic parameters, Pugh’s, and Passion’s ratios are studied to confirm materials’ mechanical stability and nature. The studied materials have been found mechanically stable and brittle. Together, our findings demonstrate the distinctive and intriguing features of Rb2AgTlX6 (X = Cl, Br) are suitable for cost-effective energy conversion applications.

β-Cyclodextrin/dialdehyde glucan-coated keratin nanoparticles for oral delivery of insulin

Successful oral insulin administration can considerably enhance the quality of life (QOL) of diabetes patients who must frequently take insulin injections. However, Oral insulin administration is seriously hampered by gastrointestinal enzymes, wide pH range, mucus and mucosal layers, which limit insulin oral bioavailability to ≤2 %. Herein, we developed a simple, inexpensive and safe dual β-cyclodextrin/dialdehyde glucan-coated keratin nanoparticle (β-CD-K-IN-DG). The resulted β-CD-K-IN-DG not only gave the ultra-high insulin loading (encapsulation efficiency (98.52 %)), but also protected insulin from acid and enzymatic degradation. This β-CD-K-IN-DG had a notable hypoglycemic effect, there was almost 80 % insulin release after 4 h of incubation under hyperglycemic conditions. Ex vivo results confirmed that β-CD-K-IN-DG possessed high mucus-penetration ability. Transepithelial transport and uptake mechanism studies revealed that bypass transport pathway and endocytosis promoted β-CD-K-IN-DG entered intestinal epithelial cells, thus increased the bioavailability of insulin (12.27 %). The improved stability of insulin during in vivo transport implied that β-CD-K-IN-DG might be a potential tool for the effective oral insulin administration.

Study of Mass Transport in the Anode of a Proton Exchange Membrane Fuel Cell with a New Hydrogen Flow‐Rate Modulation Technique

AbstractHydrogen transport in the anode of a proton‐exchange membrane fuel cell (PEMFC) has been studied with a modulation technique relating the hydrogen flow‐rate ( ) and the faradaic current ( ), called Current‐modulated Hydrogen flow‐rate Spectroscopy (CH2S). A simple analytical expression for the transfer function, H(jω)=n F / , is provided, showing a skewed semicircle in Nyquist representation (−H'' vs. H'), extending from H’=0 to H’=1, and with the maximum frequency at ωmax=2.33(DH2 /Li2), where DH2 is the effective hydrogen diffusivity and Li the thickness of the anode gas diffusion layer (GDL). The expression for CH2S is also calculated with an existing reversible chemical reaction in the GDL. Experimental results under different operation conditions show two transport processes limiting the anode reaction, one attributed to molecular diffusion through the partially saturated GDL, and the other to the microporous layer (MPL), or its interfaces with GDL or with the catalyst layer (CL). CH2S provides the hydrogen diffusivities (DH2,i) associated to each process under the different conditions. Current density decreases slightly the diffusivity of the GDL, while it becomes activated in the MPL; using two GDLs in the anode improves both GDL and MPL diffusivities; humidification decreases the diffusivity in both, GDL and MPL; finally, a superhydrophobic anodic CL prepared by electrospray improves hydrogen diffusivity in GDL and MPL.

Analysis of PM2.5, black carbon, and trace metals measurements from the Kansas City Transportation and Local-Scale Air Quality Study (KC-TRAQS)

ABSTRACT Communities near transportation sources can be impacted by higher concentrations of particulate matter (PM) and other air pollutants. Few studies have reported on air quality in complex urban environments with multiple transportation sources. To better understand these environments, the Kansas City Transportation and Local-Scale Air Quality Study (KC-TRAQS) was conducted in three neighborhoods in Southeast Kansas City, Kansas. This area has several emissions sources including transportation (railyards, vehicles, diesel trucks), light industry, commercial facilities, and residential areas. Stationary samples were collected for 1-year (October 24, 2017, to October 31, 2018) at six sites using traditional sampling methods and lower-cost air sensor packages. This work examines PM less than 2.5 μm in diameter (PM2.5), black carbon (BC), and trace metals data collected during KC-TRAQS. PM2.5 filter samples showed the highest 24-h mean concentrations (9.34 μg/m3) at the sites located within 20–50 m of the railyard. Mean 24-h PM2.5 concentrations, ranging from 7.96 to 9.34 μg/m3, at all sites were lower than that of the nearby regulatory site (9.83 μg/m3). Daily maximum PM2.5 concentrations were higher at the KC-TRAQS sites (ranging from 25.31 to 43.76 μg/m3) compared to the regulatory site (20.50 μg/m3), suggesting short-duration impacts of localized emissions sources. Across the KC-TRAQS sites, 24-h averaged PM2.5 concentrations from the sensor package (P-POD) ranged from 3.24 to 5.69 µg/m3 showing that, out-of-the-box, the PM sensor underestimated the reference concentrations. KC-TRAQS was supplemented by elemental and organic carbon (EC/OC) and trace metal analysis of filter samples. The EC/OC data suggested the presence of secondary organic aerosol formation, with the highest mean concentrations observed at the site within 20 m of the railyard. Trace metals data showed daily, monthly, and seasonal variations for iron, copper, zinc, chromium, and nickel, with elevated concentrations occurring during the summer at most of the sites. Implications: This work reports on findings from a year-long air quality study in Southeast Kansas City, Kansas to understand micro-scale air quality in neighborhoods impacted by multiple emissions sources such as transportation sources (including a large railyard operation), light industry, commercial facilities, and residential areas. While dozens of studies have reported on air quality near roadways, this work will provide more information on PM2.5, black carbon, and trace metals concentrations near other transportation sources in particular railyards. This work can also inform additional field studies near railyards.

Protein Binder Toolbox for Studies of Solute Carrier Transporters

Transporters of the solute carrier superfamily (SLCs) are responsible for the transmembrane traffic of the majority of chemical substances in cells and tissues and are therefore of fundamental biological importance. As is often the case with membrane proteins that can be heavily glycosylated, a lack of reliable high-affinity binders hinders their functional analysis. Purifying and reconstituting transmembrane proteins in their lipidic environments remains challenging and standard approaches to generate binders for multi-transmembrane proteins, such as SLCs, channels or G protein-coupled receptors (GPCRs) are lacking. While generating protein binders to 27 SLCs, we produced full length protein or cell lines as input material for binder generation by selected binder generation platforms. As a result, we obtained 525 binders for 22 SLCs. We validated the binders with a cell-based validation workflow using immunofluorescent and immunoprecipitation methods to process all obtained binders. Finally, we demonstrated the potential applications of the binders that passed our validation pipeline in structural, biochemical, and biological applications using the exemplary protein SLC12A6, an ion transporter relevant in human disease. With this work, we were able to generate easily renewable and highly specific binders against SLCs, which will greatly facilitate the study of this neglected protein family. We hope that the process will serve as blueprint for the generation of binders against the entire superfamily of SLC transporters.