Transport Studies Research Articles

Legal Reform in Legal Responsibility for the Use of Public Roads for the Transportation of Mining Products (Case Study of Transportation of Mining Products in West Aceh Regency)

Transportation plays an important role in supporting economic growth and regional connectivity, but the use of public roads for hauling activities by mining companies in West Aceh Regency has caused significant problems such as road damage, pollution, and accident risk. This condition is exacerbated by a legal vacuum at the local level that does not specifically regulate the use of public roads for the transportation of mining products, although national regulations such as the Mineral and Mineral Law and regulations related to reclamation already exist. This study uses normative juridical methods with legislative and conceptual approaches to analyze applicable legal provisions and identify legal gaps, as well as formulate legal reform solutions. The results of the study show the need for the preparation of clear regional regulations (Qanun), including the setting of operational schedules, quota systems, and real-time monitoring. In addition, the government's cooperation with business entities (PPP) to build special hauling roads through the DBOMFT scheme is proposed as a constructive solution to reduce the burden on public roads and increase regional revenue. Legal reform at the regional level is expected to provide legal certainty, protect the community, and minimize negative impacts on the environment and infrastructure.

Advancements of aquaporin 1 in ultrafiltration failure secondary to peritoneal dialysis.

For patients undergoing long-term peritoneal dialysis (PD), exposure to biologically incompatible PD solutions and the consequent peritoneal structure change can lead to progressive angiogenesis and fibrosis, and ultimately result in ultrafiltration failure (UFF). Peritoneal transport studies in aquaporin 1 (AQP1) knockout mice indicate that water transport across the peritoneum is mediated by AQP1, which accounts for up to 50% of ultrafiltration. Another recent study on a large cohort of PD patients with kidney failure further substantiated the impact of AQP1 genotype variation on water channel expression in the peritoneal membrane, influencing water transport, ultrafiltration, and patient prognosis. High-dose corticosteroid therapy in both patients and mice seems to be effective in regulating AQP1 to improve ultrafiltration. At present, increasing evidence suggests that AQP1 is relevant for the process of PD water osmotic transport and ultrafiltration. Despite a great deal of research having been done on the structure and function of aquaporin proteins, many fundamental issues remain unresolved.

EARTH-ABUNDANT 3d-TRANSITION METAL METASILICATES AS EFFECTIVE ELECTROCATALYSTS FOR ALKALINE HER: CuZnSiO3 OUTPERFORMS CuSiO3 AND ZnSiO3.

Hydrogen evolution reaction (HER) is a key reaction in electrochemical water splitting for hydrogen production leading to the development of potentially sustainable energy technology. Importantly, the catalysts required for HER must be earth-abundant for their large-scale deployment; silicates representing one such class. Herein, we have synthesized a series of transition mono- and bi- metal metasilicates (with SO32- group) using facile wet-chemical method followed by calcination at a higher temperature. The structural and morphological studies their unique crystal structure and distinctive morphology, as well as the surface texture, with the band gap ranges 1.49-2.24 eV. Interestingly, CuZnSiO3, with all earth-abundant elements, exhibits a band gap of 1.67 eV, shows impressive electrocatalytic properties. We show that CuZnSiO3 exhibits HER activity with much lower overpotential (h = 151 mV) at 10 mA cm-2 under alkaline conditions. The CuZnSiO3 electrode also shows good electrocatalytic stability (ΔE = 24 mV) even after 25 hours of chronoamperometric stability test and the performance is comparable to the commercial Pt/C catalyst under similar conditions. Finally, detailed electronic structure studies employing density functional theory (DFT) as well as electronic transport studies were performed to understand and elucidate the superior performance of CuZnSiO3 over the CuSiO3 and ZnSiO3 electrocatalysts.

Numerical study of the effects of minor structures and mean velocity fields in the cerebrospinal fluid flow

The importance of optimizing intrathecal drug delivery is highlighted by its potential to improve patient health outcomes. Findings from previous computational studies, based on an individual or a small group, may not be applicable to the wider population due to substantial geometric variability. Our study aims to circumvent this problem by evaluating an individual’s cycle-averaged Lagrangian velocity field based on the geometry of their spinal subarachnoid space. It has been shown by Lawrence et al. (J Fluid Mech 861:679–720, 2019) that dominant physical mechanisms, such as steady streaming and Stokes drift, are key to facilitating mass transport within the spinal canal. In this study, we computationally modeled pulsatile cerebrospinal fluid flow fields and Lagrangian velocity field within the spinal subarachnoid space. Our findings highlight the essential role of minor structures, such as nerve roots, denticulate ligaments, and the wavy arachnoid membrane, in modulating flow and transport dynamics within the spinal subarachnoid space. We found that these structures can enhance fluid transport. We also emphasized the need for particle tracking in computational studies of mass transport within the spinal subarachnoid space. Our research illuminates the relationship between the geometry of the spinal canal and transport dynamics, characterized by a large upward cycle-averaged Lagrangian velocity zone in the wider region of the geometry, as opposed to a downward zone in the narrower region and areas close to the wall. This highlights the potential for optimizing intrathecal injection protocols by harnessing natural flow dynamics within the spinal canal.

Genome-wide identification and expression profiling of MST, SUT and SWEET transporters in Dendrobium catenatum

BackgroundSugar transporters (STs) play a critical role in the transportation of sugar, participating in plant growth and development, stress/defense responses, and signal transduction processes. Dendrobium catenatum (also known as Dendrobium officinale, hereinafter referred to as D. catenatum) is an important traditional Chinese medicinal herb with remarkable medicinal properties and possessing high economic value. Polysaccharides are the primary active components in D. catenatum, exhibiting diverse pharmacological activities. Sugar transporters function as material supplier and may play the essential roles in the polysaccharide biosynthesis, as well as the key reulators in the signaling and responses to abiotic stresses in Dendrobium plants. However, a comprehensive analysis of sugar transporters in D. catenatum remains elusive, thereby hindering our understanding of sugar partitioning within this species.ResultsIn this work, the members belonging to MST, SUT, and SWEET gene families were identified in four Dendrobium plants. A comprehensive study of sugar transporters was conducted in D. catenatum, including phylogenetic relationship, structural arrangement, regulatory networks, expression profiles, and potential functions analysis. Seven sugar transporters were found to be involved in the process of polysaccharide biosynthesis in D. catenatum. Red-blue light is an effective way to enhance the accumulation of polysaccharides, and exerts an influence on the expression of polysaccharide biosynthesis related genes.ConclusionsThis study provide insight into the evolution and functional annotation of sugar transporters in Dendrobium, and establishing a foundation for future functional research of sugar transporters involved in polysaccharide biosynthesis and stress response.

Monitoring conformational changes in the human neurotransmitter transporter homologue LeuT with 19F-NMR spectroscopy.

Neurotransmitter:sodium symporters (NSS) reuptake neurotransmitter molecules from the synaptic space through Na+-coupled transport. They are thought to work via the alternating access mechanism, exploring multiple configurations dictated by the binding of substrates and ions. Much of the current knowledge about these transporters has been derived from examining the structure of the Leucine Transporter (LeuT), a bacterial counterpart to human NSSs. Multiple crystal structures of LeuT provided valuable information regarding the steps involved in this mechanism. Dynamical data connecting the crystal structure to the transport cycle are critical to understanding how ligands are translated through the membrane. In the present study, we applied 19F-based nuclear magnetic resonance (NMR) spectroscopy to 19F labelled LeuT to monitor how substrates and ions binding affect the conformations of the transporter. By selecting mutations and ligands known to affect the conformational equilibrium of LeuT, we identified and assigned four NMR resonances to specific conformational states of LeuT. We observe that Na+ ions produce closure of the extracellular vestibule to a state similarly induced by Na+ and substrates. Conversely, K+ ions seem to shift the conformational equilibrium toward inward-facing intermediates, arguably by competing with Na+. The present study assembles a framework for NMR-based dynamical studies of NSS transporters and demonstrates its feasibility for tackling large membrane LeuT-fold transporters.

Quantum transport study of transition-metal dichalcogenide top-contacted geometries investigating the impact of nonuniform doping, dielectric environment, and image-force barrier lowering

Quantum transport study of transition-metal dichalcogenide top-contacted geometries investigating the impact of nonuniform doping, dielectric environment, and image-force barrier lowering

Effect of Exogenous Glucose on Molecular Transport through Bacterial Membranes Studied by Second Harmonic Light Scattering.

Recent studies revealed that exogenous glucose increases the efficacy of aminoglycosides in eliminating bacterial persister cells. It was speculated that this increased antimicrobial efficacy is induced by glucose-facilitated uptake of the antibiotics. Here, we examine this hypothesis by using second-harmonic light scattering to time-resolve the transport of an antimicrobial quaternary ammonium compound (QAC), malachite green, across the membranes of living Escherichia coli (E. coli) in the presence of glucose. The results show that when the glucose concentration increased from 0 to 100 μM, the QAC transport rate constant across the cytoplasmic membrane of E. coli increased by 3.6 times. Further increase of glucose concentration into the millimolar range, however, does not further enhance the transport rate constant. Conversely, a study of QAC transport across the protein-free membrane of liposomes (constructed from the polar lipid extract of E. coli) indicates that the glucose-induced enhancement in membrane transport in E. coli is mediated by protein transporters. Cell viability experiments show that low concentration of exogenous glucose enhances the QAC efficacy in eliminating E. coli. The loss of viability of the bacterial cells in the presence of the QAC at minimum inhibitory concentration increased dramatically when glucose concentration increased from 0 to 100 μM but increasing the glucose concentration up to 1 mM did not further enhance the antimicrobial efficacy. This behavior coincides with the observed increase in QAC transport rate constant as a function of glucose concentration. These observations reveal a novel antimicrobial strategy in which low concentration glucose enhances the uptake of antimicrobials into the bacteria, thereby improving antimicrobial efficacy.

Pharmacokinetics of Maternal Drug Administration: Insights into Placental Transfer and Fetal Exposure

ABSTRACT Pregnancy profoundly influences the pharmacokinetics of maternally administered drugs, necessitating a comprehensive understanding of placental transfer and fetal exposure for safe and effective drug therapy. This review provides an updated overview of recent advancements in the field, comprising placental anatomy and physiology, pharmacokinetic changes during pregnancy, factors affecting placental transfer, techniques for studying transfer mechanisms, and clinical implications for maternal and fetal health. Recent discoveries explaining placental structure, function, and molecular transport mechanisms underscore the complexity of drug transfer across the placental barrier. Advances in pharmacokinetic research reveal dynamic alterations in drug absorption, distribution, metabolism, and excretion during pregnancy, which impact therapeutic drug levels and maternal-fetal outcomes. Factors influencing placental transfer, including drug properties, placental transporters, and maternal-fetal physiology, are increasingly recognized as critical determinants of fetal exposure. Innovative methodologies and technologies facilitate the study of placental drug transport, offering insights into drug-specific transfer kinetics and developmental risks.

Customer Satisfaction and Service Quality Assessment of Nepal Yatayat Public Buses: A Statistical Analysis of Passenger Perceptions

Background: Public transportation is vital for urban mobility, offering affordable and accessible commuting options, especially in densely populated regions. In Nepal, public buses serve a broad demographic, and understanding passenger satisfaction with services like Nepal Yatayat can provide insights for service improvements. Objective: This study aims to analyze customer satisfaction with the Nepal Yatayat bus service, examining factors such as comfort, safety, cleanliness, punctuality, and overall service reliability. The goal is to identify key areas for improvement to enhance user experience and promote public transport use. Methods: The study utilized a quantitative approach through a structured questionnaire distributed to 92 respondents. Data analysis was conducted using SPSS software, where various statistical tools such as correlation and reliability analysis assessed relationships between demographic factors and satisfaction variables. Findings: The majority of respondents were young adults aged 18-24 (75.8%), predominantly male (65.9%), with a significant portion holding bachelor's degrees (49.5%) and most being unemployed (61.8%). 59.4% of respondents expressed discomfort with bus seating and internal space arrangements, while 78.1% reported dissatisfaction or uncertainty about cleanliness standards. About 42.9% felt safe on Nepal Yatayat buses, while 30.8% were dissatisfied with punctuality. 37.7% of respondents rated staff behavior poorly, indicating a need for improvement in professionalism. Overcrowding was a significant concern, with 67.1% agreeing that buses were frequently crowded, and 45.1% believed the bus station locations were appropriate. : Reliability was rated as medium by 77.2% of respondents, with moderate recommendations for the service among users (40.7% likely to recommend). Conclusion: The analysis reveals that Nepal Yatayat requires improvements in comfort, cleanliness, safety, and punctuality to enhance passenger satisfaction. Crowding and staff professionalism are also key areas where service modifications could significantly impact commuter perceptions. Novelty: This study provides a detailed and empirical assessment of passenger satisfaction specifically with Nepal Yatayat, addressing service dimensions such as comfort, cleanliness, safety, and route effectiveness, previously underexplored in public transport studies within Nepal.

Elastic wave transport in angularly selective valley topological metamaterials plate

The valley degree of freedom has attracted increasing attention in elastic wave systems owing to its energy extrema at valleys and great potential in energy transportation. This study investigated the transport of valley edge states by angularly selective excitation in elastic wave metamaterials plate and designed a bifunctional elastic wave device in the bent waveguide containing two different interfaces. The supercell analysis revealed that the valley edge states exhibit symmetrical and anti-symmetrical distributions at two different interfaces. The straight and bent waveguides containing a single interface are designed, and the selective transport of valley edge states is observed due to the symmetrical or anti-symmetrical distributions at the interfaces. The angularly selective excitation of valley edge states by external excitation is demonstrated at the straight and bent interfaces. Based on these transport characteristics of valley edge states and the valley conservation mechanism, a bifunctional elastic wave device composed of a bent waveguide containing both two interfaces is designed. It can realize both the functions of the diode and the backward diode. The designed elastic wave device has the advantages of being a single structure with bifunctions. This study of topological valley transport with angularly selective characteristic may also have practical applications such as energy harvesting and sensing.

Transport Studies of the Innovative Vertical Buoy Supported Risers System

The current expansion of offshore oil and gas exploration in increasingly deeper water depths leads to an option of utilization of hybrid riser systems. These systems are characterized by the combination of flexible jumpers and Steel Catenary Risers (SCRs), interconnected by a floating submerged structure. Among the offered types of hybrid riser systems, one of them employs a Buoy Supported Risers (BSR) as an intermediate element between the flexible jumpers and the SCRs. Although the hybrid riser system utilizing the BSR manages the advantages associated with both types of risers, providing a very effective ultradeep waters riser system, the use of the BSR entails high costs, complexity, and considerable risk during the transportation and installation stages of the buoy. In this way, new alternatives regarding the use of hybrid risers are welcome. In this context, this work presents the innovative proposal of a Vertical Buoy Supported Risers (VBSR) that may offer greater viability when compared to the traditional horizontal concepts, resulting in benefits for hybrid riser systems and, consequently, for oil and gas exploration activities in deepwater environments. The benefits of vertical configuration of the BSR, in relation to the conventional horizontal one, are more focused on transport and installation risks reduction, although also presents vantages in operational phase. In this work, the presented study is focused on the transport stage of the VBSR. Therefore, an evaluation of the VBSR’s static and dynamic responses during transportation in intact and damage scenario are presented here.

Model-Based Study of Near-Surface Transport in and around Cape Cod Bay, Its Seasonal Variability, and Response to Wind

Abstract Output from a high-resolution numerical model is used to study near-surface transport in and around Cape Cod Bay using a Lagrangian approach. Key questions include the following: What are the dominant transport pathways? How do they vary in time on seasonal-to-interannual scales? What is the role of wind in driving this variability? Application to a possible release of wastewater into Cape Cod Bay from the recently closed Pilgrim Nuclear Power Station is discussed. Analysis reveals a seasonality in Cape Cod Bay transport patterns, with shorter residence times throughout the bay and an increased probability of outflow waters exiting the bay during spring and summer. Wind-induced Ekman currents are identified as a dominant driver of this variability. Significance Statement This study is motivated by a possible release of radioisotope-contaminated wastewater into Cape Cod Bay, a region important to fishing, aquaculture, and tourist industries. The specific aim is to better understand near-surface transport patterns and mechanisms in Cape Cod Bay both in general and within the context of a wastewater release from Pilgrim Nuclear Power Station.

Study of Sand Transport in a Horizontal Pipeline Using Validated Computational Fluid Dynamics Simulations with Experimental Fiber-Optic Distributed Acoustic Sensing Data

Summary Sand management in wellbores is a significant challenge in the industry, notably impacting equipment integrity and operational safety—particularly in offshore oil and gas operations affected by the onset of sand production along with hydrocarbons. Recent advancements in fiber-optic sensing, especially through distributed acoustic sensing (DAS) experimental data, have enabled the continuous monitoring of sand ingress and migration. In this study, we use computational fluid dynamics (CFD) to accurately model sand transport by validating the simulations against the DAS data in a 40-ft-long, 2-in.-diameter experimental flow loop. The validation and verification (V&V) process demonstrates the CFD model’s accuracy in both steady-state and transient conditions, through predictions of key flow parameters such as sand slip velocity, sand concentration profiles, and sand arrival times against published experimental data, as well as verification of CFD methodology against similar simulation studies. Next, we used the CFD model to simulate the fiber-optic experimental DAS data for sand slurry transport in a pipe through an injection port with conditions of carrier fluid velocity = 0.93 m/s and dispersed phase (sand) particle diameter of 300 µm at a concentration of 0.001 v/v. To address uncertainties during sand production, a parametric study under transient conditions was conducted with varying boundary conditions in the CFD model. It examined fluid flow velocities at both 0.53 m/s and 0.93 m/s, below and above the critical settling velocity of the sand respectively, and the effects of varying sand particle diameters (125 µm and 600 µm). Our research represents a significant advancement in sand management strategies, offering a robust and cost-effective tool for simulating real-world scenarios to improve operational efficiency. By providing detailed insights into flow dynamics and enabling robust predictions across various conditions, this study contributes substantially to advancing sand management strategies that could effectively mitigate operational risks and optimize sand transport in real time.

Epitaxial films and devices of transparent conducting oxides: La:BaSnO3

This paper reviews recent developments in materials science and device physics of high-quality epitaxial films of the transparent perovskite La-doped barium stannate, La:BaSnO3. It presents current efforts in the synthesis science of epitaxial La:BaSnO3 films for achieving reduced defect densities and high electron mobility at room temperature. We discuss the scattering mechanisms and the route toward engineering defect-free epitaxial La:BaSnO3 heterostructures. By combining chemical surface characterization and electronic transport studies, special emphasis is laid on the proper correlation between the transport properties and the electronic band structure of La:BaSnO3 films and heterostructures. For application purposes, interesting optical properties of La:BaSnO3 films are discussed. Finally, for their potential application in oxide electronics, an overview of current progress in the fabrication of La:BaSnO3-based thin-film field-effect transistors is presented together with recent progress in the fundamental realization of two-dimensional electron gases with high electron mobility in La:BaSnO3-based heterostructures. Future experimental studies to reveal the potential deployment of La:BaSnO3 films in optoelectronic and transparent electronics are also discussed.

Particle size and settling velocity of bed and suspended sediments for mud-sand beds

The particle size and the settling velocity of sediments are key parameters in sediment transport studies. However, it remains surprisingly difficult to determine particle size and settling velocity distribution of fine-grained sediments (mud-sand). A large range of methodologies exist to measure either the particle size distribution or to measure the settling velocity. An important influential parameter is the shape of fine-grained sediments, with clay minerals being shaped as plates rather than as spheres. Furthermore, the settling velocity of fine particles is influenced by turbulent shear and flocculation processes. Sometimes, the sediment samples are pre-treated (destroying inter-particle bonds) to measure the primary particle sizes involved while in other cases samples are not pre-treated in order to represent the effect of flocs. As a result, a large uncertainty exists in the way particle size and settling velocity should be measured. A range of methodologies (sedimentation, video camera, and laser-diffraction) to measure the settling velocity and particle size distribution in the field and in the laboratory is used and compared. The labour-intensive sedimentation methods measure a particle size distribution which can be used for sedimentation studies. The particle size distribution measured by the most commonly applied laser diffraction method is representative of the plate diameter of the clay particles, but the corresponding settling velocity is not correct. This difference can be explained by the shape of the clay particles through a derivation of the settling velocity of non-spherical particles resulting in a simple relationship to convert the particle size measured by laser diffraction to a representative particle size to be used in sedimentation studies. A comparison of the settling velocity measured by an in situ settling method and by a video camera method shows good agreement for high concentrations (> 2000 mg/L) but deviating results for low concentrations (< 500 mg/L).

Solution-processed tungsten diselenide as an inorganic hole transport material for moisture-stable perovskite solar cells in the n-i-p architecture

Some of the obstacles to the commercialization of perovskite solar cells (PSCs) are their long-term moisture stability and material cost of the constituent layers, such as the commonly used spiro-OMeTAD hole transport layer (HTL). Replacing the spiro-OMeTAD with low-cost inorganic hole transport materials (HTMs) are important to further elevate the attractiveness of PSCs for commercialization. Perovskite-compatible, solution-exfoliated two-dimensional (2D) transition metal dichalcogenides (TMDCs) are being considered as viable candidates for inorganic HTMs. We consider one such TMDC, WSe2 which was chemically exfoliated using dichlorobenzene (DCB), a perovskite-compatible solvent, as it was integrated with triple cation perovskite absorbers within the solar cell stack. The WSe2 HTL required heat treatment processes to be maintained below 100 °C in order to preserve the integrity of the underlying perovskite; despite this lower temperature post treatment process, the structural morphology of the film revealed its dense and pinhole-free nature. Temperature-dependent transport studies conducted on the WSe2 film provided evidence of its semiconducting character and its ability to extract holes well from the underlying triple-cation Cs0.05FA0.79MA0.16PbI2.45Br0.55 absorber. The inorganic HTL offered better environmental stability in moisture-rich environments of up to 60 % relative humidity, in comparison to spiro-OMeTAD HTL-based devices which degraded faster as a result of pinholes.

Unraveling the relation between carbon emission and carbon footprint: A literature review and framework for sustainable transportation

Transportation decarbonization has drawn enormous attention globally, and two concepts play vital roles: transportation carbon emission (TCE) and transportation carbon footprint (TCF). However, their overlapping definitions and mixed uses in relevant literature have caused ambiguities and misunderstandings, resulting in a pressing need to clarify their subtle relationships in a more introspective manner. Therefore, we performed an in-depth literature review to investigate their essential commonalities and differences, with a focus on two aspects: understanding the scientific progress in terms of research trends, foci, and clusters to capture their connotations and use cases; and diagnosing how they are inherently estimated and how misuses can be alleviated. Accordingly, we developed an integrated life cycle analytical framework to relate TCE and TCF in an interdisciplinary landscape. Implications regarding systematic and explicit quantification standards were identified and discussed. Finally, we proposed three research gaps and four possible directions for future sustainable transportation studies.

Topological nodal line features in NiSe semimetal: Insights from electronic transport and density functional theory studies

Topological nodal line features in NiSe semimetal: Insights from electronic transport and density functional theory studies

Spin transport of a doped Mott insulator in moiré heterostructures

Moiré superlattices of semiconducting transition metal dichalcogenide heterobilayers are model systems for investigating strongly correlated electronic phenomena. Specifically, WSe2/WS2 moiré superlattices have emerged as a quantum simulator for the two-dimensional extended Hubbard model. Experimental studies of charge transport have revealed correlated Mott insulator and generalized Wigner crystal states, but spin transport of the moiré heterostructure has not yet been sufficiently explored. Here, we use spatially and temporally resolved circular dichroism spectroscopy to directly image the spin transport as a function of carrier doping and temperature in WSe2/WS2 moiré heterostructures. We observe diffusive spin transport at all hole concentrations at 11 Kelvin — including the Mott insulator at one hole per moiré unit cell — where charge transport is strongly suppressed. At elevated temperatures the spin diffusion constant remains unchanged in the Mott insulator state, but it increases significantly at finite doping away from the Mott state. The doping- and temperature-dependent spin transport can be qualitatively understood using a t–J model, where spins can move via the hopping of spin-carrying charges and via the exchange interaction.