Initial Density Research Articles

Compression Molding Characteristics of Seed Cotton and Damage from Cottonseed Crushing

This study investigated the impact of compression molding parameters on the post-molding characteristics of machine-harvested seed cotton and aimed to determine the optimal compression molding parameters. The closed compression test of seed cotton and force analysis on a single cottonseed clarified the boundary conditions for cottonseed crushing and the relationship between crushing rate and compressive force. A seed cotton compression test bench facilitated single-factor and four-factor, three-level quadratic regression orthogonal experiments, varying the moisture content, initial density, compression force, and holding time. Variance analysis revealed each factor’s influence on the dimensional stability coefficient. Utilizing Design Expert 13.0.5, the optimal compression molding parameter ranges were identified: 6–11.7% moisture content, 47.87–74.84 kg/m3 initial density, 3–5.32 kN compression force, and 50–239.75 s holding time. Software predictions within this range indicated an optimal cottonseed crushing rate and dimensional stability coefficient of 2.853% and 3.274, respectively. Further verification experiments yielded a cottonseed crushing rate and dimensional stability coefficient of 2.888% and 3.282, respectively, with a maximum error of 3.85%, validating the model and optimized parameters. Therefore, strictly controlling seed cotton compression molding parameters was shown to reduce the cottonseed crushing rate and dimensional stability coefficient. These findings offer crucial theoretical insights for developing seed cotton compression processes and selecting parameters for cotton harvesting and packing devices.

Temporal evolution of the light emitted by a thin, laser-ionized plasma source

We present an experimental and simulation-based investigation of the temporal evolution of light emission from a thin, laser-ionized helium plasma source. We demonstrate an analytic model to calculate the approximate scaling of the time-integrated, on-axis light emission with the initial plasma density and temperature, supported by the experiment, which enhances the understanding of plasma light measurement for plasma wakefield accelerator (PWFA) plasma sources. Our model simulates the plasma density and temperature using a split-step Fourier code and a particle-in-cell code. A fluid simulation is then used to model the plasma and neutral density, and the electron temperature as a function of time and position. We then show the numerical results of the space-and-time-resolved light emission and that collisional excitation is the dominant source of light emission. We validate our model by measuring the light emitted by a laser-ionized plasma using a novel statistical method capable of resolving the nanosecond-scale temporal dynamics of the plasma light using a cost-effective camera with microsecond-scale timing jitter. This method is ideal for deployment in the high radiation environment of a particle accelerator that precludes the use of expensive nanosecond-gated cameras. Our results show that our models can effectively simulate the dynamics of a thin, laser-ionized plasma source. In addition, this work provides a detailed understanding of the plasma light measurement, which is one of the few diagnostic signals available for the direct measurement of PWFA plasma sources.

Densely accessible single atom Fe sites dispersed on porous carbon as highly stable and active ORR catalyst for PEMFC

Single-atom Fe–N–C catalysts have received ever-growing interest in proton exchange membrane fuel cells (PEMFCs) application for their utmost atomic utilization in oxygen reduction reaction (ORR). However, developing atomically dispersed Fe–N–C catalysts with both satisfactory activity and excellent stability presents great challenges. Herein, a template-activator combined strategy is developed to construct ORR catalysts with densely accessible single-atom Fe sites dispersed on hierarchically porous carbon networks. The optimized catalyst exhibits excellent oxygen reduction activity with a half-wave potential of 0.84 V and surprising stability with 93.6% retention of the initial current density after 24 hours of chronoamperometric test in acidic media. Notably, when assembled in a H2–O2 fuel cell, it shows remarkable long-term durability with only 16% loss in current density during the first 10 hours.

Ion-collection characteristics of photoplasma for atomic vapor laser isotope separator module in electrostatic fields

The laser-based isotope separation process is currently pursued to enrich precursor medical isotopes like lutetium-176 and ytterbium-176. India has successfully produced radionuclide lutetium-177 for clinical use by neutron activation. Atomic vapor laser isotope separation (AVLIS) is used as the enrichment technology. Understanding the physics and technology of processes, like atomic-beam generation, photoplasma production, and ion collection, is essential to designing any AVLIS module. So, a stand-alone research facility was developed before the production plant. This article describes the facility and the experimental and theoretical studies of ion collection in electrostatic fields using barium as the working element. Two types of ion extractors, plate–photoplasma–plate and plate–photoplasma–grid–plate, were designed and fabricated. A model of photo-ion collection in these electrostatic ion extractors was arrived at. Scaling of the initial photo-ion densities and the electric fields is crucial to photoplasma evolution spanning single-particle to collective regimes. Estimates of ion-collection rates of the Indian AVLIS modules for lutetium-176 and ytterbium-176 were carried out. By invoking plasma physics, the technological aspect of producing enriched isotopes was solved by judiciously integrating the atom source, laser system, photoplasma, and ion-extractor geometries. Limitations of the electrostatic ion extractors were also flagged.

Wavefront distortion and compensation for weakly relativistic vortex beams propagating in plasma

The propagation of electromagnetic wave in plasma is one of the long-standing concerns in the field of laser plasma, and it is closely related to the researches of radiation source generation, particle acceleration, and inertial confinement fusion. Recently, the proposal of various schemes for generating intense vortex beams has led to an increasing number of researchers focusing on the interaction between intense vortex beams and plasmas, resulting in significant research progress in various areas, such as particle acceleration, high-order harmonic generation, quasi-static self-generated magnetic fields, and parametric instability. Compared with traditional Gaussian beams, vortex beams, featuring their hollow amplitudes and helical phases, can exhibit novel phenomena during propagating through plasma. In this work, we primarily focus on studying the influence of the propagation process on the wave structure of vortex beams before filamentation occurs. The three-dimensional particle-in-cell simulations show that weakly relativistic vortex beams exhibit wavefront distortion during their propagation in plasma. The distortion degree is closely related to the intensity of the electromagnetic wave and the propagation distance for a given plasma density. This phenomenon is theoretically explained by using a phase correction model that considers the relativistic mass correction of electrons. Additionally, we demonstrate that the wavefront distortion can be compensated for and suppressed by appropriately modulating the initial plasma density, as confirmed by three-dimensional particle simulations. The results of decomposing the wavefront into Laguerre-Gaussian (LG) mode components indicate that the wavefront distortion is primarily caused by high-order <i>p</i> LG modes, and it is independent of other <i>l</i> LG modes. Additionally, we extend the present investigation to the propagation of vortex beams in axially magnetized plasma, where the phase correction model can also effectively explain the occurrence of wavefront distortion. Our work can deepen the understanding of the interaction between plasma and strong vortex beams, and provide some valuable references for designing plasma devices serving as the manipulation of intense vortex beams in future research.

Structural features and dynamic behaviour of the interlayer space of layered double hydroxide coatings

Layered double hydroxide (LDH) offer great potentialities to design functional coatings with customizable properties by exploiting their anion exchange properties. We investigated the anion exchange properties and expansion capacity of the interlayer space relating to the starting film morphology. ZnAl LDH coatings of different thicknesses and morphologies were first obtained by an in situ method using Al-based substrates. When the anion to intercalate is relatively bigger than the starting nitrates, the intercalation may be constrained by the initial LDH particle size and density composing the film. After optimising the morphology, the intercalation of three functional anions with potential antimicrobial properties was successfully achieved with an expansion of the interlayer space up to 150 % while holding the coating integrity. The release of the guest anion was studied by immersion in physiological saline solution. Finally, the possibility to regenerate the coating was demonstrated supporting the potential of these hybrid coatings for applications.

Investigation of plasma parameters, distributions, and optical emission for the anti-microbial performance of non-woven fabric under direct current glow discharge

The distribution of electron temperature Te and density Ne for direct current glow plasma discharge was investigated, using a single Langmuir probe, inserted inside the plasma cell. The radial temperature distribution has the same values, except with a small increment variation at the cathode edge, and an axial decrement for the temperature Te distribution profiles from the cathode fall region, passing the abnormal glow region, up to the faraway axial region.The radial distribution of the electron density Ne has its highest value at the cathode, with very intense plasma at the cathode fall region, and more Ne decrement in the abnormal glow region, passing the abnormal glow region up to the faraway axial region. In the axial Ne distribution, an increase in Ne from the cathode fall region reaches maximum values in the abnormal glow region and decreases in the faraway axial region.The optimal plasma surface treatment of non-woven silk fabric (n-WSF) can be achieved by utilizing a high plasma density and low energy of electrons to inactivate viable cells attached to (n-WSF) at very short application times, leading to complete inactivation, where the bacterial inactivation rate increases in the abnormal glow region. Based on analyses of the experimental data of initial and final densities of viable cells using survival curves in the abnormal glow discharge region, a dramatic inhibitory effect of plasma discharge on the residual survival microbe ratio was observed.

Performance and characterization of snail adhesive mucus as a bioflocculant against toxic Microcystis

Toxic Microcystis blooms are widespread in aquatic bodies, posing major threats to aquatic and human life. Recently, bioflocculants have attracted considerable attention as a promising biomaterial for Microcystis management. In search of a novel organism that can produce an efficient bioflocculant for controlling harmful algae sustainably, the native gastropod Cipangopaludina chinensis was co-cultured continuously with toxic Microcystis under different initial algal cell densities. The bioflocculation effect of snail mucus on toxic Microcystis, microcystin removal, and toxin accumulation in snails was investigated. In addition, the properties of the adhesive mucus were characterized using microscopic, X-ray diffraction, infrared spectroscopy, and polysaccharide and proteome analyses. Microcystis cells were captured and flocculated by the snail mucus; removal efficiencies of up to 89.9% and 84.8% were achieved for microalgae and microcystin-leucine arginine (MC-LR), respectively, when co-cultured with C. chinensis for only one day. After nine-day exposure, less than 5.49 µg/kg DW microcystins accumulated in the snails, indicating safety for human consumption. The snail mucus contained 104.3 µg/mg protein and 72.7 µg/mg carbohydrate, which provide several functional groups beneficial for Microcystis bioflocculation. The main monosaccharide subunits of polysaccharides are galactose, galactosamine, glucosamine, fucose, glucose, and mannose. Most of them are key components of polysaccharides in many bioflocculants. Gene Ontology analysis indicated the protein enrichment in binding processes and catalytic activity, which may account for Microcystis bioflocculation via protein binding or enzymatic reactions. The findings indicate that native C. chinensis secretes adhesive mucus that can act as bioflocculant for toxic Microcystis from ambient water and can be an effective and eco-friendly tool for Microcystis suppression.

Harvesting a population model with Allee effect in a periodically varying environment

<abstract><p>A nonautonomous logistic population model with a feature of an Allee threshold has been investigated in a periodically fluctuating environment. A slow periodicity of the harvesting effort was considered and may arise in response to relatively slow fluctuations of the environment. This assumption permits obtaining the analytical approximate solutions of such model using the perturbation approach based on the slow variation. Thus, the analytical expressions of the population evolution in the situation of subcritical and the supercritical harvesting were obtained and discussed in the framework of the Allee effect. Since the exact solution was not available due to the nonlinearity of the system, the numerical computation was considered to validate our analytical approximation. The comparison between the two methods showed a remarkable agreement as the time progressed, while such agreement fell off when the time was close to the initial density. Moreover, in the absence of the periodicity of the harvesting term, the expressions of the population evolution reduced to the exact solutions but in implicit forms. The finding results were appropriate for a wide range of parameter values, which lead to avoiding extensive recalculations while displaying the population behavior.</p></abstract>

Energy processes and phase transition in granular assemblies

Granular assemblies are an illustrative example of complex material where unexpected macroscopic properties may emerge when they are subjected to a given loading. The complexity is the consequence of the huge geometrical disorder governed by particle rearrangements, entailing plastic dissipation at contacts. This local dissipation, associated with the global geometric disorder, is probably a key ingredient responsible for various macroscopic features, such as the strain localization in dense granular assemblies leading to the formation of a shear band. Based on a discrete element method (DEM), this manuscript investigates the energy processes at the microscopic scale in granular assemblies along biaxial loading paths for dense and loose assemblies. The localized shear band domain in a dense specimen is inspected. The analysis of elastic processes suggests a maximum capacity for storing elastic energy, giving rise to a phase transition from a homogeneous state to a heterogeneous one. This phase transition is marked by a significant release of elastic energy associated with plastic dissipation. The elastic-to-plastic energy transfer is shown to be a key ingredient to reach the stationary state regime characterized by a unique dynamic equilibrium. It is signaled by the constant ratios of elastic storage and plastic dissipation over the available energy, whatever the initial density of granular assemblies. Finally, the energy processes inside the shear band domain are shown to be largely dominated by intense plastic dissipation. This suggests that the shear band acts as an optimal dissipative structure in dense specimens where elastic mechanisms continue to be active at a much higher level than they are in the outside shear band domain.

Phase-space simulations of prompt cusps: simulating the formation of the first haloes without artificial fragmentation

ABSTRACT The first generation of haloes forms from the collapse of the smallest peaks in the initial density field. N-body simulations of this process suggest a prompt formation of a steep power-law cusp, but these calculations are plagued by numerical artefacts that cast some doubt on this result. Here, we develop new simulation methods based on the dark matter phase-space sheet approach and present results that are entirely free of artificial clumps. We find that a cusp with density ρ ∝ r−1.5 is indeed formed promptly, subsequently accreting a more extended halo and participating in the hierarchical growth of later halo generations. However, our simulations also suggest that the presence of artificial clumps just before peak collapse can significantly shallow the inner profiles of the cusps. We use N-body simulations with controlled amounts of small-scale power to place a conservative upper limit on the scales affected by artificial clumps. Finally, we used these results to simulate the collapse of the first generation of peaks of various types and in different cosmologies, finding prompt cusps to form in all cases. We conclude that prompt cusps are a generic feature of the collapse of peaks on the free-streaming scale of the initial density field, and their structure can safely be studied using N-body simulations provided care is taken to excise the region potentially affected by artificial clumps.

Antibacterial Effect of Basil (Ocimum basilicum) and Table Salt as Alternative Disinfectants against Staphylococcus aureus

This study was undertaken to evaluate the potency of basil (Ocimum basilicum) extract and table salt as alternative disinfectants based on their effect in inhibiting bacterial proliferation. A sample of bacteria (Staphylococcus aureus) with an initial mean density of 1.35 x 103 CFU/mL was used as the bacterial test culture. Treatments included basil extract (T1), table salt (T2), ethanol (T3, positive control) and distilled water (T4, negative control). The antibacterial effect of the treatments was evaluated in terms of the measurement of the zones of inhibition which was further validated by monitoring the mean recovery counts of bacteria post-application with the treatments given at different concentrations (100, 50, 25 and 10%). The results showed that the larger diameter of the zones of inhibition (with mean measurements that ranged from 17.65 to 20.98 mm) was related to the application of basil extract, table salt and ethanol applied at 100% concentration compared with the 50% (mean measurements ranged from 14.03 to 17.67 mm) underscoring the minimum inhibitory concentration of the candidate disinfectants at 50%. There was a comparable significant reduction of bacterial recovery counts associated with the application of basil extract and ethanol only at 3 h that were not sustained until 6 h. The results indicated that basil extract and table salt at the prescribed concentrations could be used and therefore recommended as disinfectants.

Comparing the removal efficiency of diisobutyl phthalate by Bacillariophyta, Cyanophyta and Chlorophyta

The utilization of microalgae for both removing phthalate esters (PAEs) from wastewater and producing bioenergy has become a popular research topic. However, there is a lack of studies comparing the effectiveness of different types of microalgae in removing these harmful compounds. Therefore, the present study aimed to evaluate and compare the efficiency of various processes, such as hydrolysis, photolysis, adsorption, and biodegradation, in removing diisobutyl phthalate (DiBP) using six different species of microalgae. The study indicated that the average removal efficiency of DiBP (initial concentrations of 5, 0.5, and 0.05 mg L−1) by all six microalgae (initial cell density of 1 × 106 cells mL−1) was in the order of Scenedesmus obliquus (95.39 %) > Chlorella vulgaris (94.78 %) > Chroococcus sp. (91.16 %) > Cyclotella sp. (89.32 %) > Nitzschia sp. (88.38 %) > Nostoc sp. (84.33 %). The results of both hydrolysis and photolysis experiments revealed that the removal of DiBP had minimal impact, with respective removal efficiencies of only 0.89 % and 1.82 %. The adsorption efficiency of all six microalgae decreased significantly with increasing initial DiBP concentrations, while the biodegradation efficiency was elevated. Chlorella vulgaris and Chroococcus sp. demonstrated the highest adsorption and biodegradation efficiencies among the microalgae tested. Scenedesmus obliquus was chosen for the analysis of the degradation products of DiBP due to its exceptional ability to remove DiBP. The analysis yielded valuable results, identifying monoisobutyl phthalate (MiBP), phthalic acid (PA), and salicylic acid (SA) as the possible degradation products of DiBP. The possible degradation pathways mainly included dealkylation, the addition of hydroxyl groups, and decarboxylation. This study lays a theoretical foundation for the elimination of PAEs in the aquatic environment.

MOF-Derived Trifunctional High Entropy Sulfides as an Electrocatalyst for Alkaline Unitized Regenerative Fuel Cell Application

Electrochemical devices such as electrolyzers (EL), fuel cells (FC), metal-air batteries (MAB), and unitized regenerative fuel cells (URFC) are key components in our drive toward a renewable energy-based power infrastructure. The potential scale of these devices requires the usage of catalytic materials that exhibit not only excellent catalytic activity but also commendable durability. Conventional precious metal catalysts such as Pt, Ir, Rh, Ru, and Pd are utilized for variable deployments during electrocatalysis. 1 Recent trends in alloying, tuning the band structure, nanosizing of particles, and application of earth-abundant transition metals, have immensely increased the economic feasibility and practical applications of a new genre of electrochemical devices. 2 Here, strategically designed materials, such as metal-organic frameworks (MOF), offers a new route for synthesizing the alloys and their derivatives with high porosities and excellent catalytic activity. 3 High entropy alloys (HEA) containing multiple (four or more) components of metallic oxides, sulfides, and phosphides have emerged as a new class of materials. Effects such as lattice distortion, entropy stabilization, cocktail effect, and formation of multiple oxidation states in such HEA enable access to multiple catalytic centers for catalyzing more than one small molecule activation reaction. 4 The current work focuses on the synthesis of FeCuCoMnNi-based high entropy sulfide (HES) via a unique MOF route. This HES material successfully demonstrates three distinct catalytic reactions: oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). The surface morphology and phase of the HES can be critically curated via sulfurizing the multi-metal MOF precursor, which was monitored with a battery of surface characterization techniques. This HES displayed an impressive bifunctionality index of 0.80 V and 1.87 V for application in alkaline URFC (ORR/OER) and EL (HER/OER), where moderate to low overpotentials were observed for OER (η OER = 380 mV), ORR (η ORR = 420 mV), and HER (η HER = 260 mV). The superior electrochemical performance of this HES is attributed to the surface reconstruction mechanism upon the inclusion of transition metals such as Fe, Co, and Mn to Ni leading to the formation of the key Ni-OOH layer. Along with excellent performance, the HES exhibited good durability at +1.5 V vs. RHE up to 12 hours while retaining ~75% of the initial current density, indicating the presence of a high configurational entropy in the material. References Huynh, M., Ozel, T., Liu, C., Lau, E. C., & Nocera, D. G. 2017 Chemical science, 8(7), 4779-4794.Xu, J., Li, J., Xiong, D., Zhang, B., Liu, Y., Wu, K. H., ... & Liu, L. 2018 Chemical science, 9(14), 3470-3476.Karmakar, A., Kumar, N., Samanta, P., Desai, A. V., & Ghosh, S. K. 2016 Chemistry–A European Journal, 22(3), 864-868.Miracle, D. B., Miller, J. D., Senkov, O. N., Woodward, C., Uchic, M. D., & Tiley, J. 2014 Entropy, 16(1), 494-525 Figure 1

(Invited) Durable and Highly Active Fe-N-C Catalysts for PEM Fuel Cells

Atomically dispersed and nitrogen-coordinated single iron sites (FeN4) embedded in carbon (Fe-N-C) catalysts are the most promising platinum group metal (PGM)-free catalysts. However, they have yet to match their Pt counterparts for oxygen reduction reaction (ORR) activity and stability in proton exchange membrane fuel cells (PEMFCs). Here, we developed viable Fe-N-C catalysts, which, for the first time, demonstrated competitive activity to that of Pt/C catalysts and dramatically enhanced stability and durability under practical PEMFC operating conditions. The most active Fe-N-C catalyst achieved a record half-wave potential (E1/2 = 0.915 V vs. RHE at 0.6 mgcatcm-2) and an ORR mass activity of 10.5 mA mgcat at 0.9 V in (RDE) tests, exceeding a Pt/C baseline catalyst (60 µgPt cm-2) by 40 mV in acidic electrolytes. This compelling activity of the Fe-N-C catalyst in aqueous acids on rotating disk electrode (RDE) was successfully transferred to fuel cell membrane electrode assembly (MEAs), generating an initial current density of 44.2 mA cm-2 exceeding the U.S. DOE 2025 target (i.e., 44 mA cm-2) at 0.9 VIR-free under O2. Under practical hydrogen-air conditions, record 151 mA cm-2 at 0.8 V and peak power density of 601 mW cm-2 were achieved. Importantly, we discovered that depositing nitrogen-carbon species on the catalyst surface via chemical vapor deposition (CVD) dramatically enhanced catalyst stability, evidenced by performance durability after accelerated stress tests (30 000 square-wave voltage cycles under H2/air) and long-term steady-state life tests (> 300 hours at 0.67 V). Innovative identical location-scanning transmission electron microscopy (IL-STEM) experiments confirmed that the CVD process leads to deposition of nitrogen-doped carbon onto the catalyst surfaces. Along with theoretical modeling, a reconstruction of the carbon structure adjacent to FeN4 sites leads to increased robustness against demetallation and carbon oxidation. This work opens new avenues for developing earth-abundant iron-based catalysts with extraordinary activity and stability, thus competing with Pt and addressing the cost barrier of current PEMFCs.

A comparative study of advanced oxidation-based hybrid technologies for industrial wastewater treatment: An engineering perspective

In this paper, several advanced oxidation-based hybrid technologies were employed to efficiently remove organic pollutants from industrial wastewater. First, the efficiency of hybrid treatment systems composed of coagulation-flocculation, electrochemical oxidation (ECO), and ozone oxidation for removal of several landfill leachates were investigated and the effects of coagulation-flocculation with different chemicals, including polyaluminum chloride, anionic polymers, calcium-based compounds, and sodium carbonate were studied. Coagulation-flocculation/ECO/Ozone oxidation hybrid system achieved the best performance (90.65% removal rate) for fluoride removal, compared with ECO alone and coagulation-flocculation/ECO systems. With a 92.2% fluoride removal rate, Ca(OH)2 achieved the best performance among all calcium-based hybrid treatment technologies. Then, the role of Fenton oxidation/adsorption hybrid technologies in industrial wastewater treatment were also investigated and compared with adsorption and Fenton oxidation alone. Fenton oxidation-adsorption technology achieved a high TOC removal rate of 97%, which was 2.42 times higher than that obtained by activated carbon alone (41.4%) and 1.56 times higher than that achieved by the homogeneous FO process alone (63%). Finally, factors influencing the efficiency of pollutant degradation, including initial pH value, pollutant concentration, and current density were evaluated.

A dislocation-density-based crystal plasticity model for FCC nanocrystalline metals incorporating thermally-activated depinning from grain boundaries

A novel dislocation-density-based crystal plasticity model for nanocrystalline face-centered cubic metals is developed based on the thermally-activated mechanism of dislocations depinning from grain boundaries. Dislocations nucleated from grain boundary dislocation sources are assumed to be the primary carriers of plasticity in the nanocrystals. The evolution of the dislocation density thereby involves a competition between the nucleation of dislocations from grain boundary defect structures, such as ledges, and the absorption of dislocations into the grain boundary via diffusion processes. This model facilitates the simulation of plastic deformation in nanocrystalline metals, with consideration of the initial microstructure resulting from a particular processing method, to be computed as a direct result of dislocation-mediated plasticity only. The exclusion of grain boundary-mediated plasticity mechanisms in the formulation of the crystal plasticity model allows for the exploration of the fundamental role dislocations play in nanocrystalline plasticity. The combined effect of average grain size, grain size distribution shape, and initial dislocation density on the mechanical performance and strain-rate sensitivity are explored with the model. Further, the influence of the grain boundary diffusivity on post-yielding strain-hardening behavior is investigated to discern the impact that the choice of processing route has on the resulting deformation response of the material.

Improving Stability of CO2 Electroreduction by Incorporating Ag NPs in N-Doped Ordered Mesoporous Carbon Structures.

The electroreduction of carbon dioxide (eCO2RR) to CO using Ag nanoparticles as an electrocatalyst is promising as an industrial carbon capture and utilization (CCU) technique to mitigate CO2 emissions. Nevertheless, the long-term stability of these Ag nanoparticles has been insufficient despite initial high Faradaic efficiencies and/or partial current densities. To improve the stability, we evaluated an up-scalable and easily tunable synthesis route to deposit low-weight percentages of Ag nanoparticles (NPs) on and into the framework of a nitrogen-doped ordered mesoporous carbon (NOMC) structure. By exploiting this so-called nanoparticle confinement strategy, the nanoparticle mobility under operation is strongly reduced. As a result, particle detachment and agglomeration, two of the most pronounced electrocatalytic degradation mechanisms, are (partially) blocked and catalyst durability is improved. Several synthesis parameters, such as the anchoring agent, the weight percentage of Ag NPs, and the type of carbonaceous support material, were modified in a controlled manner to evaluate their respective impact on the overall electrochemical performance, with a strong emphasis on operational stability. The resulting powders were evaluated through electrochemical and physicochemical characterization methods, including X-ray diffraction (XRD), N2-physisorption, Inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy (SEM), SEM-energy-dispersive X-ray spectroscopy (SEM-EDS), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), STEM-EDS, electron tomography, and X-ray photoelectron spectroscopy (XPS). The optimized Ag/soft-NOMC catalysts showed both a promising selectivity (∼80%) and stability compared with commercial Ag NPs while decreasing the loading of the transition metal by more than 50%. The stability of both the 5 and 10 wt % Ag/soft-NOMC catalysts showed considerable improvements by anchoring the Ag NPs on and into a NOMC framework, resulting in a 267% improvement in CO selectivity after 72 h (despite initial losses) compared to commercial Ag NPs. These results demonstrate the promising strategy of anchoring Ag NPs to improve the CO selectivity during prolonged experiments due to the reduced mobility of the Ag NPs and thus enhanced stability.

A data-driven, scenario-based human evacuation model for passenger ships addressing hybrid uncertainty

In a disaster at sea, the safe and timely removal of passengers from the ship is paramount. Here, a human evacuation plan enables passengers to be swiftly displaced from a risk area to one less so. Despite existing research on evacuation planning, there is a need for a more comprehensive model that considers various uncertainties and factors. This paper proposes an optimization evacuation model that balances uncertain variables, including passenger walking speed and travel distance, and deterministic factors like deck layout, door capacity, initial density, and corridor traffic flow. The model also accounts for varying starting locations and two levels of awareness—alert and non-alert. The model utilizes a data-driven technique, i.e., the k-means algorithm, to cluster historical data on speeds and generate scenarios. An adjustment scheme is applied to account for the ship's rolling motion, affecting passenger speeds during the evacuation planning period. Travel distance scenarios are produced to capture the impact of different route choices per passenger. A risk-neutral two-stage programming model is constructed to handle uncertainties. The model is tested on multiple problems for a passenger ship deck in day and night modes, revealing valuable managerial insights for the maritime safety sector.

Global solvability and stabilization in a three-dimensional coral fertilization model involving the Navier-Stokes equations

This paper deals with a coral fertilization model involving the Navier-Stokes equations. It is proved that an associated initial-boundary value problem with no-flux, Dirichlet boundary conditions in a three-dimensional smoothly bounded domain admits a globally defined weak solution for any appropriately regular initial data whenevermax⁡{‖c0‖∞,‖m0‖∞}<π2χ, where χ is the chemotaxis sensitivity and m0,c0 are initial density of unfertilized eggs and initial concentration of the chemical expelled by the eggs, respectively. Moreover, it is showed that the obtained solutions stabilize to a certain constant equilibrium.