Heterogeneous Surface Research Articles

Flow resistance over heterogeneous roughness made of spanwise-alternating sandpaper strips

The Reynolds number dependent flow resistance of heterogeneous rough surfaces is largely unknown at present. The present work provides novel reference data for spanwise-alternating sandpaper strips as one idealised case of a heterogeneous rough surface. Experimental data are presented and analysed in direct comparison with drag measurements of homogeneous sandpaper surfaces and numerical simulations. Based on the homogeneous roughness data, the related challenges and sensitivities for the evaluation of roughness functions from experiments and simulations are discussed. A hydraulic channel height is suggested as an alternative measure for the drag impact of rough surfaces in internal flows. For the investigated heterogeneous roughness, it is found that turbulent flow does not exhibit a fully rough flow behaviour, indicating that the assignment of an equivalent sand grain height as commonly applied for homogeneous roughness is not possible. A prediction of the drag behaviour of rough strips based on an average between rough and smooth drag curves appears promising, but requires further refinement to capture the impact of turbulent secondary flows and spatial transients linking smooth and rough surface parts. While turbulent secondary flow induced by the roughness strips yield significant spanwise variation of the mean velocity profile for the investigated rough strips, we show that the spanwise averaged velocity profiles collapse reasonably well with a smooth or homogeneous rough wall flow. This allows to extract a global roughness function from the spanwise averaged flow field in good agreement with the one deduced from global pressure drop measurements.

The geometric evolution of aortic dissections: Predicting surgical success using fluctuations in integrated Gaussian curvature.

Clinical imaging modalities are a mainstay of modern disease management, but the full utilization of imaging-based data remains elusive. Aortic disease is defined by anatomic scalars quantifying aortic size, even though aortic disease progression initiates complex shape changes. We present an imaging-based geometric descriptor, inspired by fundamental ideas from topology and soft-matter physics that captures dynamic shape evolution. The aorta is reduced to a two-dimensional mathematical surface in space whose geometry is fully characterized by the local principal curvatures. Disease causes deviation from the smooth bent cylindrical shape of normal aortas, leading to a family of highly heterogeneous surfaces of varying shapes and sizes. To deconvolute changes in shape from size, the shape is characterized using integrated Gaussian curvature or total curvature. The fluctuation in total curvature (δK) across aortic surfaces captures heterogeneous morphologic evolution by characterizing local shape changes. We discover that aortic morphology evolves with a power-law defined behavior with rapidly increasing δK forming the hallmark of aortic disease. Divergent δK is seen for highly diseased aortas indicative of impending topologic catastrophe or aortic rupture. We also show that aortic size (surface area or enclosed aortic volume) scales as a generalized cylinder for all shapes. Classification accuracy for predicting aortic disease state (normal, diseased with successful surgery, and diseased with failed surgical outcomes) is 92.8±1.7%. The analysis of δK can be applied on any three-dimensional geometric structure and thus may be extended to other clinical problems of characterizing disease through captured anatomic changes.

Efficient and selective separation of Re(VII), an analogue of Tc(VII), by a defective biochar with honeycomb‐like porous structure

AbstractBACKGROUNDIn this study, a defective biochar with honeycomb‐like porous structure (BC‐PH) was successfully prepared by the activation of pristine biochar derived from bamboo shoot shell with the chemical reagent KOH, and was applied to selectively separate ReO4− (a chemical analogue for radioactive TcO4−) from acidic solutions.RESULTSThe diffusion, mass transfer and recovery for ReO4− could be significantly improved by the large specific surface area (SBET, 2412 m2 g−1) and high total volume (Vtot, 1.26 cm3 g−1) of BC‐PH. The influence of adsorbent dosage, system pH and coexisting ions with different valence states on the adsorption capability and selectivity of BC‐PH toward ReO4− was systematically investigated. BC‐PH exhibited high adsorption capacity and selectivity for ReO4− with a maximal sorption capacity (qm) of 73.11 mg g−1 at initial pH 2. By applying an analysis of kinetics and isotherm adsorption studies, the liquid film diffusion was verified to be the primary rate‐controlling step for the sorption of ReO4− and the multilayer adsorption process occurred on the heterogeneous surface of BC‐PH. Besides, the recovery of ReO4− using BC‐PH occurred in an exothermic and spontaneous manner according to thermodynamic analysis. Furthermore, an investigation of the adsorption mechanism suggested that pore filling and electron donor–acceptor interaction were mainly related to the removal of ReO4−.CONCLUSIONThese results suggest that BC‐PH has great potential for the application of TcO4− separation in consideration of its high adsorption capacity and selectivity. © 2024 Society of Chemical Industry (SCI).

Airborne Measurements of Scale‐Dependent Latent Heat Flux Impacted by Water Vapor and Vertical Velocity Over Heterogeneous Land Surfaces During the CHEESEHEAD19 Campaign

AbstractThe water vapor transport associated with latent heat flux (LE) in the planetary boundary layer (PBL) is critical for the atmospheric hydrological cycle, radiation balance, and cloud formation. The spatiotemporal variability of LE and water vapor mixing ratio (rv) are poorly understood due to the scale‐dependent and nonlinear atmospheric transport responses to land surface heterogeneity. Here, airborne in situ measurements with the wavelet technique are utilized to investigate scale‐dependent relationships among LE, vertical velocity (w) variance (), and rv variance () over a heterogeneous surface during the Chequamegon Heterogeneous Ecosystem Energy‐balance Study Enabled by a High‐density Extensive Array of Detectors 2019 (CHEESEHEAD19) field campaign. Our findings reveal distinct scale distributions of LE, , and at 100 m height, with a majority scale range of 120 m–4 km in LE, 32 m–2 km in , and 200 m–8 km in . The scales are classified into three scale ranges, the turbulent scale (8–200 m), large‐eddy scale (200 m–2 km), and mesoscale (2–8 km) to evaluate scale‐resolved LE contributed by and . The large‐eddy scale in PBL contributes over 70% of the monthly mean total LE with equal parts (50%) of contributions from and . The monthly temporal variations mainly come from the first two major contributing classified scales in LE, , and . These results confirm the dominant role of the large‐eddy scale in the PBL in the vertical moisture transport from the surface to the PBL, while the mesoscale is shown to contribute an additional ∼20%. This analysis complements published scale‐dependent LE variations, which lack detailed scale‐dependent vertical velocity and moisture information.

Cooperative Time-Varying Formation Fuzzy Tracking Control of Multiple Heterogeneous Uncertain Marine Surface Vehicles With Actuator Failures.

This article addresses the cooperative time-varying formation fuzzy tracking control problem for a cluster of heterogeneous multiple marine surface vehicles subject to unknown nonlinearity and actuator failures. The proposed cooperative control scheme consists of two parts: 1) a distributed time-varying formation observer and 2) a decentralized adaptive fuzzy tracking controller. The distributed observer is designed to obtain a predefined time-varying formation pattern under a directed communication topology. Subsequently, based on the states of the distributed observer, a decentralized fuzzy tracking control law is developed using fuzzy-logic systems and the adaptive approach. Lyapunov functions are constructed to guarantee that the controlled marine vehicles attain the desired time-varying formation with asymptotical stability of tracking errors. Finally, simulation results are presented to validate the efficacy of the proposed control methodology.

Surface Heterogeneity, Physical, and Shape Model of Near-Earth Asteroid (52768) 1998 OR2

On 2020 April 29, the near-Earth object (52768) 1998 OR2 experienced a close approach to Earth at a distance of 16.4 lunar distances (LD). 1998 OR2 is a potentially hazardous asteroid of absolute magnitude H = 16.04 that can currently come as close to Earth as 3.4 LD. We report here observations of this object in polarimetry, photometry, and radar. Our observations show that the physical characteristics of 1998 OR2 are similar to those of both M- and S-type asteroids. Arecibo’s radar observations provide a high radar albedo of σˆOC= 0.29 ± 0.08, suggesting that metals are present in 1998 OR2 near-surface. We find a circular polarization ratio of μ c = 0.291 ± 0.012, and the delay-Doppler images show that the surface of 1998 OR2 is a top-shape asteroid with large-scale structures such as large craters and concavities. The polarimetric observations display a consistent variation of the polarimetric response as a function of the rotational phase, suggesting that the surface of 1998 OR2 is heterogeneous. Color observations suggest an X-complex taxonomy in the Bus–DeMeo classification. Combining optical polarization, radar, and two epochs from the NEOWISE satellite observations, we derived an equivalent diameter of D = 1.80 ± 0.1 km and a visual albedo p v = 0.21 ± 0.02. Photometric and radar data provide a sidereal rotation period of P = 4.10872 ± 0.00001 hr, a pole orientation of (332.°3 ± 5°, 20.°7 ± 5°), and a shape model with dimensions of (2.08−0.10+0.10,1.93−0.10+0.10,1.60−0.05+0.05) km.

Comparison of Forecasting Biases Over New York State Mesonet: A Wet Summer Versus a Dry Summer

AbstractExtreme weather events are occurring with increasing frequent due to the climate change. This increasing frequency may introduce more uncertainty in weather forecasting model performance, particularly when considering the intricate relationship of the land surface and atmosphere coupling system. In this study, we utilize data from the sophisticated New York State Mesonet to evaluate the performance of a forecasting system based on WRF Version 4 model, drawing insights from both dry and wet summers. Additionally, the model's performance is assessed on two land surface types: forest and farmland, to provide a comprehensive evaluation of impact of land surface heterogeneity. The surface meteorology, fluxes, and cloud development are assessed. The coupling between surface and atmosphere is diagnosed using a mixing diagram which serves to represent surface thermodynamic properties. The results reveal a systematic increase in warm season dry and warm biases, especially for forested sites during a drought year. The model exhibits heightened sensitivity to drought conditions, resulting in a substantial underestimation of latent heat fluxes during such period. During days with boundary layer clouds, the mixing diagram shows a notably slower growth of moist static energy in the model compared to observation. It is possible that these biases partly attribute to the underestimation of cloud optical depth due to not enough energy for the cloud development.

In situ synthesis of tentacle-like NiC/Mo2C/NF nanorods array with excellent hydrogen evolution reaction at high current densities

The problem limiting the use of hydrogen evolution reactions in industry is the inability of electrocatalysts to operate stably at high current densities, so the development of stable and efficient electrocatalysts is important for hydrogen production by water splitting. By designing a rational interface engineering not only can the problem of limited number of catalytic sites in the catalyst be solved, but also can facilitate electron transfer, thus enhancing the efficiency of water splitting. Here, we designed a two-stage chemical vapour deposition method to construct NiC/Mo2C nanorod arrays on nickel foam to enhance the electrocatalytic ability of the catalysts, which exhibited efficient HER catalytic activity due to their special tentacle-like nanorod structure and abundant heterogeneous junction surfaces, which brought about abundant active sites as well as promoted electron transfer capability. The resulting catalysts provide current densities of 10, 100 and 500 mA cm−2 with overpotentials of 31, 153 and 264 mV, and exhibit excellent stability at current densities of 10 mA cm−2 for 200 h. This discovery provides a new idea for the rational design of catalysts with special morphologies.

Effect of synthesis conditions on the porous texture of activated carbons obtained from Tara Rubber by FeCl3 activation

This paper presents the results of an unique analysis of the influence of the mass ratio of activator FeCl3 to precursor and the temperature of the activation process on the formation of the porous structure of activated carbons obtained from Tara Rubber by FeCl3 activation. The study used the new numerical clustering based adsorption analysis method and the quenched solid density functional theory, taking into account, among other things, the heterogeneity of the analysed surface which is a new approach rarely used in the analysis of the porous structure of adsorbents. On the basis of the calculation results, it was concluded that the activated carbon with the most developed porous texture was obtained at a mass ratio (FeCl3:Tara Rubber) of 2, at an activation process temperature of 800 °C. This activated carbon is also characterised by the lowest degree of surface heterogeneity and at the same time, however, the widest range of micropores compared to activated carbons obtained at other mass ratios. The analyses carried out further demonstrated the valuable and complementary information obtained from the structure analysis methods and their high utility in practical applications, especially in the development of new industrial technologies for the production of adsorbents and the selection of optimal conditions for their production.

Spectral mixture analysis of intimate mixtures for lithological mapping

Spectral mixing is frequently encountered in remotely sensed images while imaging heterogeneous surfaces. Spectral mixing occurs at the macroscopic level due to the sensor’s low spatial resolution or multiple reflections from materials received by the sensor. Due to the mixing effect, retrieving the information of spectral endmembers becomes complicated. In this study, two different unmixing methods: (i) linear mixing models (LMM) and (ii) the Hapke nonlinear mixing model, were used to quantitatively estimate the fractional abundance of various rock types that will be helpful in remotely mapping the mineral prospects. Three types of constraints using the least square approach were applied independently to LMM and Hapke models, namely FCLS (sum to unity and nonnegativity constrained), NNLS (nonnegativity constrained), and UCLS (unconstrained). AVIRIS-NG (Airborne Visible and InfraRed Imaging Spectrometer-Next Generation) and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) images from the Sittampundi anorthosite complex (SAC) were utilised for the spectral mixture analysis. Few studies are available on the anorthosite rocks of Sittampundi as an analogue to the Lunar anorthosite. The study area is known for its chromite deposits occurring in pyroxenite rocks. Therefore, in the present study, endmembers considered are anorthosite and pyroxenite/metagabbro.The moderately dense vegetation cover of the study area obscures the detection of rock outcrops on the surface. The study area exhibits nonlinear spectral mixing effects due to the vegetation cover. Hence apart from the two rock endmembers, vegetation is also considered as an endmembers in spectral mixture analysis. The results show a high fractional abundance of vegetation and anorthosite throughout the study region, with the pyroxenite/metagabbro mainly concentrated over the western and eastern regions. The Hapke model shows more accurate results than LMM on the AVIRIS-NG image. The Hapke model outperforms LMM in accurately retrieving the fractional abundance of endmembers due to the nonlinear spectral mixing effects caused by vegetation. Additionally, the constrained least squares methods, i.e., FCLS and NNLS, performed better than UCLS in linear and nonlinear mixing models, resulting in accurate and reliable abundance maps. AVIRIS-NG outperformed the ASTER images in fractional abundance mapping of endmembers, highlighting the importance of utilising higher spatial and spectral resolution data for more reliable land cover and lithology mapping. Overall, this study demonstrates the potential of spectral mixture analysis in identifying geologic outcrops in vegetation-covered regions. Hence, the methodology presented in this study benefits the lithological mapping of vegetation-covered regions and has wide applications in quantitatively assessing the lithology of mineral prospects.

Heterogeneity in millimeter-scale Ti-6Al-4V lattice primitives: Challenges in defining effective properties for metamaterial design

The effective design of metallic metamaterials, characterized by interconnected struts or 'lattices,' hinges on the ability to predict strut and strut intersection ('node') responses. This is critical for predicting the macroscopic properties of structures comprised of thousands of struts. Computationally efficient beam descriptions, defined by strut properties like cross-sectional area, modulus, and yield stress, can significantly expedite the prediction of lattice structures and ultimately enable topology optimization. This paper provides a comprehensive examination of the properties of electron-beam melted three-dimensional printed struts and their 'nodes'—four intersecting struts. The findings elucidate the efficacy of various strategies for defining effective properties that accurately capture mechanical response. The study reveals that using a single set of effective properties can introduce inconsistencies between strut stiffness, peak load, and critical displacement. Stiffness correlates with averaged cross-sectional areas, while the peak load capacity correlates more closely with minimum inscribed cross-sectional areas. Analysis of nodes indicates that the interaction of surface defects and heterogeneity within the node strongly influences multi-strut response. Data from CT scans, EBSD scans, and nanoindentation maps highlight spatial variations comparable to the strut diameter, posing a significant challenge in defining effective homogenized properties. This study emphasizes the need for future efforts to integrate statistical property distributions with high throughput simulations to overcome the difficulty in defining a representative volume element (RVE) at the strut scale.

Acid insoluble lignin material production by chemical activation of olive endocarps for an efficient furfural adsorption-removal from aqueous solutions

The present work describes a protocol of chemical activation, with acid catalyst, of olive endocarps to obtain acid insoluble lignin-rich materials with high capacities for the adsorption of furfural present in aqueous media. During biomass activation, factors such as acid concentration, reaction time and temperature, solid/liquid ratio and the presence of water extractives strongly affected both the surface characteristics of the treated bioadsorbents and their capacities for furfural retention (percentage increase close to 600% with respect to the crude biomass). Once a treated solid with good adsorbent properties was obtained, the optimal conditions for adsorption were found: stirring speed 80 rpm, temperature 303 K and adsorbent load 7.5 g solid/50 cm3. Kinetic study indicated the pseudo-second order model provided the best fit of the experimental data. At 303 K, the equilibrium adsorption capacities values ranged from 2.27 mg g−1 to 29.29 mg g−1, for initial furfural concentrations between 0.49 g dm−3 and 12.88 g dm−3. Freundlich model presented the best isotherm (R2 = 0.996 and SE = 4.7%) providing KF and n values of 0.115 (mg g−1) (mg dm−3)−n and 0.610, respectively. Since physical interactions predominate in the adsorption of furfural on chemically activated olive endocarps, the furfural removal process could have occurred reversibly on the heterogeneous surface of the bioadsorbents.

Designer Nanoreactors for Bioorthogonal Catalysis.

The evolutionary complexity of compartmentalized biostructures (such as cells and organelles) endows life-sustaining multistep chemical cascades and intricate living functionalities. Relatively, within a very short time span, a synthetic paradigm has resulted in tremendous growth in controlling the materials at different length scales (molecular, nano, micro, and macro), improving mechanistic understanding and setting the design principals toward different compositions, configurations, and structures, and in turn fine-tuning their optoelectronic and catalytic properties for targeted applications. Bioorthogonal catalysis offers a highly versatile toolkit for biochemical modulation and the capability to perform new-to-nature reactions inside living systems, endowing augmented functions. However, conventional catalysts have limitations to control the reactions under physiological conditions due to the hostile bioenvironment. The present account details the development of bioapplicable multicomponent designer nanoreactors (NRs), where the compositions, morphologies, interfacial active sites, and microenvironments around different metal nanocatalysts can be precisely controlled by novel nanospace-confined chemistries. Different architectures of porous, hollow, and open-mouth silica-based nano-housings facilitate the accommodation, protection, and selective access of different nanoscale metal-based catalytic sites. The modular porosity/composition, optical transparency, thermal insulation, and nontoxicity of silica are highly useful. Moreover, large macropores or cavities can also be occupied by enzymes (for chemoenzymatic cascades) and selectivity enhancers (for stimuli-responsive gating) along with the metal nanocatalysts. Further, it is crucial to selectively activate and control catalytic reactions by a remotely operable biocompatible energy source. Integration of highly coupled plasmonic (Au) components having few-nanometer structural features (gaps, cavities, and junctions as electromagnetic hot-spots) endows an opportunity to efficiently harness low-power NIR light and selectively supply energy to the interfacial catalytic sites through localized photothermal and electronic effects. Different plasmonically integrated NRs with customizable plasmonic-catalytic components, cavities inside bilayer nanospaces, and metal-laminated nanocrystals inside hollow silica can perform NIR-/light-induced catalytic reactions in complex media including living cells. In addition, magnetothermia-induced NRs by selective growth of catalytic metals on a pre-installed superparamagnetic iron-oxide core inside a hollow-porous silica shell endowed the opportunity to apply AMF as a bioorthogonal stimulus to promote catalytic reactions. By combining "plasmonic-catalytic" and "magnetic-catalytic" components within a single NR, two distinct reaction steps can be desirably controlled by two energy sources (NIR light and AMF) of distinct energy regimes. The capability to perform multistep organic molecular transformations in harmony with the natural living system will reveal novel reaction schemes for in cellulo synthesis of active drug and bioimaging probes. Well-designed nanoscale discrete architectures of NRs can facilitate spatiotemporal control over abiotic chemical synthesis without adversely affecting the cell viability. However, in-depth understanding of heterogeneous surface catalytic reactions, rate induction mechanisms, selectivity control pathways, and targeted nanobio interactions is necessary. The broad field of biomedical engineering can hugely benefit from the aid of novel nanomaterials with chemistry-based designs and the synthesis of engineered NRs performing unique bioorthogonal chemistry functions.

Solving Heterogeneous USV Scheduling Problems by Problem-Specific Knowledge Based Meta-Heuristics with Q-Learning

This study focuses on the scheduling problem of heterogeneous unmanned surface vehicles (USVs) with obstacle avoidance pretreatment. The goal is to minimize the overall maximum completion time of USVs. First, we develop a mathematical model for the problem. Second, with obstacles, an A* algorithm is employed to generate a path between two points where tasks need to be performed. Third, three meta-heuristics, i.e., simulated annealing (SA), genetic algorithm (GA), and harmony search (HS), are employed and improved to solve the problems. Based on problem-specific knowledge, nine local search operators are designed to improve the performance of the proposed algorithms. In each iteration, three Q-learning strategies are used to select high-quality local search operators. We aim to improve the performance of meta-heuristics by using Q-learning-based local search operators. Finally, 13 instances with different scales are adopted to validate the effectiveness of the proposed strategies. We compare with the classical meta-heuristics and the existing meta-heuristics. The proposed meta-heuristics with Q-learning are overall better than the compared ones. The results and comparisons show that HS with the second Q-learning, HS + QL2, exhibits the strongest competitiveness (the smallest mean rank value 1.00) among 15 algorithms.

Evaluation of aqueous phase adsorption of Acid Brown on mesoporous activated carbon prepared from Azolla Pinnate seaweed

<p>A mesoporous activated carbon was produced from the Azolla Pinnate (AP) seaweed by two-step chemical activation technique using sulphuric acid as activating agent. The adsorption of Acid Brown (AB) from aqueous solutions is examined using the produced carbon (AP). The produced activated carbon renders a homogeneous porous structure, predominantly mesoporous with 686.5 m2/g of BET surface area. The infra-red spectrum revealed AB affinity by multiple functional groups. The point of zero charge and the pH studies evidenced that the surface charge responsible for electronic affinity favours adsorption at higher pH. The SEM and FTIR analysis of AP before and after adsorption of acid brown shows multiple interactions, which is further substantiated by equilibrium, kinetic and thermodynamic models. Equilibrium adsorption data matched best with Langmuir isotherm model, thus primarily follows chemical interaction. However, physical affinity and heterogeneity of surface and species interaction also do exist nearly equally. Pseudo-second order kinetics provided the best explanation of the adsorption kinetics. The temperature variation studies revealed that acid brown adsorption is endothermic with high surface affinity.</p>

Modeling flow through tubes and annuli with liquid‐infused surfaces for enhanced stability of the fluid‐fluid interface

AbstractSuperhydrophobic (SHS) and liquid‐infused surfaces (LIS) have shown great potential in various engineering applications. Due to their heterogeneous surface properties, a mathematical description of the flow behavior along such surfaces is challenging. Circular textured surfaces are of particular importance. They are modeled as either axially traversed tubes or annuli consisting of no‐slip walls that are padded with rotationally symmetric finite‐shear regions. The latter represents a viscous interaction zone with a second fluid, assumed with layer thickness zero. Zimmermann and Schönecker provide analytical equations that describe the flow field and effective slip length for such geometries. They are applicable to Newtonian fluids of arbitrary viscosity ratio. This article emphasizes the development of principles and guidelines for the design of SHS and LIS to enhance sliding effects, based on these analytical models. The approach presented here facilitates an geometric evaluation of slippery circular surfaces, aiming to offer insights for the design. Through this research, the potential for significant energy savings and enhanced fluid transport performance can be realized, contributing to the development of more efficient fluid engineering systems.

Gamma radiation‐induced synthesis of polyaniline/CuWO4 nanocomposite for potential sorption of cobalt‐60 and cesium‐137 from aqueous solutions

The release of cobalt‐60 and cesium‐137 in the environment is considered dangerous pollutants. In this concern, the present work deals with gamma radiation‐induced synthesis of novel polyaniline/CuWO4 (PANi/CWO) nanocomposite adsorbent and estimating its potential adsorption capacity for cobalt‐60 and cesium‐137 from aqueous solution. The crystallite size of pure CWO NPs and PANi/CWO nanocomposite is found in the nanoscale range. Also, SEM images and XRD results confirmed the successful preparation of PANi/CWO nanocomposite. Further, the elemental mapping images proved that all the investigated elements were homogeneously distributed over the PANi/CWO nanocomposite. Besides, the adsorption experiments were conducted separately to investigate the adsorption behavior of cobalt‐60 and cesium‐137 by PANi/CWO nanocomposite. Adsorption processes have also been performed, and numerous factors, including medium pH, contact time, initial metal ion concentration, and temperature, have been tested. Batch experiments were done to get the optimum conditions for removing cobalt‐60 and cesium‐137. Four kinetic models were investigated, indicating that the adsorption process of cobalt‐60 and cesium‐137 onto PANi/CWO nanocomposite is controlled by chemisorption and intra‐particle diffusion. Four equilibrium isotherm models were investigated, revealing that the adsorption process is a monolayer and multilayer process on a heterogeneous surface. The (∆Ho) value suggested that this study's removal of cesium and cobalt has an endothermic behavior, whereas the positive (∆So) value proved that the examined system is random. The effect of temperature was investigated, and the calculated thermodynamic parameters indicated that the removal of cobalt‐60 and cesium‐137 by PANi/CWO nanocomposite has an endothermic behavior.

A molecular-level mechanistic framework for interfacial proton-coupled electron transfer kinetics.

Electrochemical proton-coupled electron transfer (PCET) reactions can proceed via an outer-sphere electron transfer to solution (OS-PCET) or through an inner-sphere mechanism by interfacial polarization of surface-bound active sites (I-PCET). Although OS-PCET has been extensively studied with molecular insight, the inherent heterogeneity of surfaces impedes molecular-level understanding of I-PCET. Herein we employ graphite-conjugated carboxylic acids (GC-COOH) as molecularly well-defined hosts of I-PCET to isolate the intrinsic kinetics of I-PCET. We measure I-PCET rates across the entire pH range, uncovering a V-shaped pH-dependence that lacks the pH-independent regions characteristic of OS-PCET. Accordingly, we develop a mechanistic model for I-PCET that invokes concerted PCET involving hydronium/water or water/hydroxide donor/acceptor pairs, capturing the entire dataset with only four adjustable parameters. We find that I-PCET is fourfold faster with hydronium/water than water/hydroxide, while both reactions display similarly high charge transfer coefficients, indicating late proton transfer transition states. These studies highlight the key mechanistic distinctions between I-PCET and OS-PCET, providing a framework for understanding and modelling more complex multistep I-PCET reactions critical to energy conversion and catalysis.

Direct numerical simulation of momentum and scalar internal boundary layers

Direct numerical simulations (DNS) of turbulent open channel flow are performed to study and compare momentum and scalar internal boundary layers (IBL). An internal boundary layer (IBL) forms when a turbulent boundary layer is subjected to heterogeneous surface conditions. For example, a momentum IBL forms with a change in surface roughness and a scalar IBL forms due to a localised heat flux. Momentum IBLs are simulated using both a streamwise-varying roughness body forcing technique and a streamwise-varying wall shear stress. Passive scalar IBLs are simulated using both streamwise-varying scalar wall values and wall fluxes, for a homogeneous smooth wall. The roughness body forcing model is shown to reproduce the same IBL features as with the explicitly resolved roughness study of Rouhi et al. (2019), but at a reduced cost. Three common IBL detection methods are employed to estimate the power-law exponents in the growth rates of the IBL. The exponents for the momentum IBL cases are typically less than 0.7 for these methods, smaller than for the scalar-analogues of these methods. Furthermore, we analyse the streamwise variation of the root-mean-square wall-normal (vertical) velocity. We find that the ‘diffusion analogy’, or that momentum and scalar IBLs behave similarly, may not be an appropriate assumption, especially for rough-to-smooth transitions for momentum IBLs.

Microwave energy assisted fabrication and characterization of 45S5 bioglass-ceramics using bio-wastes as alternative resources for biomedical applications

This work presents a novel approach for the fabrication and characterization of 45S5 bioglass-ceramics using rice husk ash (RHA) and eggshell ash (EGSA) as alternative resources at varying inclusions. In this study, RHA and EGSA, which are abundant agricultural waste products, are utilized to synthesize 45S5 bioglass through a microwave energy-assisted melt-quenching approach and sintered at temperatures of 950, 1000 and 1050 °C respectively. The obtained bioglass-ceramics (BGCs) were characterized for their structure, mechanical properties, morphology, antibacterial properties, and bioactivity. The results showed the developed BGCs exhibited a broad hump base with sharp crystalline peaks. The morphology showed irregular morphology containing heterogeneous grains, rough and porous surface respectively, essential for bone in-growth and cell infiltration, while a cauliflower-like appearance of carbonate-hydroxyapatite was well pronounced on all the samples after immersion in simulated body fluid. The developed BGCs also showed improved mechanical properties with increased sintering temperature and antibacterial properties to justify their use for biomedical applications.