Energy Input Research Articles

Thermospheric nitric oxide energy budget during extreme geomagnetic storms: a comparative study

We selected three superstorms (disturbance storm time [Dst] index less than −350 nT) of 2003–04 to study the thermospheric energy budget with a particular emphasis on the thermospheric cooling emission by nitric oxide via a wavelength of 5.3 μm. The nitric oxide radiative emission data are obtained from the Sounding of the Atmosphere by Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite and the thermosphere ionosphere electrodynamic general circulation model (TIEGCM) simulation. Different energy sources for the magnetospheric energy injection and the thermospheric/ionospheric dissipation processes are calculated using empirical formulations, model simulations, and space-borne and ground-based measurements. The Joule heating rates calculated from different sources showed similar variations but significant differences in the magnitude. The nitric oxide cooling power is calculated by zonally and meridionally integrating the cooling flux in the altitude range of 100–250 km. The satellite observed that cooling flux responds faster to the energy input, as compared to the modeled results. The cooling power increases by an order of magnitude during storm time with maximum radiation observed during the recovery phase. Both the satellite-observed and modeled cooling powers show a strong positive correlation with the Joule heating power during the main phase of the storm. It is found that the maximum radiative power does not occur during the strongest storm, and it strongly depends on the duration of the main phase. The model simulation predicts a higher cooling power than that predicted by the observation. During a typical superstorm, on average, a cooling power of 1.87 × 105 GW exiting the thermosphere is estimated by the TIEGCM simulation. On average, it is about 40% higher than the satellite observation.

Supercontinuum generation in a graded-index multimode tellurite fiber

We report the generation of a broadband supercontinuum (SC) from 790 to 2900 nm in a tellurite graded-index (GRIN) multimode fiber with a nanostructured core. We study the SC dynamics in different dispersion regimes and observe near-single-mode spatial intensity distribution at high input energy values. Numerical simulations of the (3 + 1)D generalized nonlinear Schrödinger equation are in good agreement with our experiments. Our results open a new avenue for the generation of high-power mid-infrared SC sources in soft-glass fibers.

Scalable Jet‐Based Fabrication of PEI‐Hydrogel Particles for CO2 Capture

The capture, regeneration, and conversion of CO2 from ambient air and flue gas streams are critical aspects of mitigating global warming. Solid sorbents for CO2 absorption are very promising as they have high mass transfer areas without energy input and reduce emissions and minimize corrosion as compared to liquid sorbents. However, precisely tunable solid CO2 sorbents are difficult to produce. Here, we demonstrate the high‐throughput production of hydrogel‐based CO2‐absorbing particles via liquid jetting. By wrapping a liquid jet consisting of an aqueous solution of cross‐linkable branched polyethylenimine (PEI) with a layer of suspension containing hydrophobic silica nanoparticles, monodisperse droplets with a silica nanoparticle coating layer was formed in the air. A stable Pickering emulsion containing PEI droplets was obtained after these ejected droplets were collected in a heated oil bath. The droplets turn into mm‐sized particles after thermal curing in the bath. The diameter, PEI content, and silica content of the particles were systematically varied, and their CO2 absorption was measured as a function of time. Steam regeneration of the particles enabled cyclic testing, revealing a CO2 absorption capacity of 6.5 ± 0.5 mol kg−1 solid PEI in pure CO2 environments and 0.7 ± 0.3 mol kg−1 solid PEI for direct air capture. Several thousands of particles were produced per second at a rate of around 0.5 kg per hour, with a single nozzle. This process can be further scaled by parallelization. The complete toolbox for the design, fabrication, testing, and regeneration of functional hydrogel particles provides a powerful route toward novel solid sorbents for regenerative CO2 capture.

Application of resource-environmental-economic perspective for optimal water and nitrogen rate under high-low seedbed cultivation in winter wheat

High-low seedbed cultivation (HLSC), a targeted agricultural method for increasing land utilization efficiency in North China Plain, has emerged as a key practice in enhancing sustainable agriculture, particularly in the context of the region’s unique ecological challenges and water scarcity. However, comprehensive analysis of resource-environment-economy for water and nitrogen strategy in HLSC-cultivated wheat was limited. A three-year field experiment with four nitrogen rates (360, 300, 240, and 180 kg ha−1, denoted as N1, N2, N3, and N4) and three irrigation quotas (120, 90, and 60 mm, referred to as W1, W2, and W3) was conducted to investigate effects of water and nitrogen rate on water productivity (WP), agronomic efficiency of nitrogen (AEN), energy use efficiency (EUE), carbon footprint (CF), water footprint (WF), nitrogen footprint (NF), and net benefits of HLSC-cultivated wheat. Results showed that the total energy output in moderate water and nitrogen input (i.e., N3W2) was 328.0×103 MJ ha−1, which was significantly increased by 31.8% compared with lower input (i.e., N4W3) but was decreased by 17.1% compared with higher input (i.e., N1W1). The total energy input, water consumption and grain yield in N3W2 was decreased by 22.3%, 14.4 and 4.1%, relative to N1W1, respectively, and increased by 18.2%, 20.8% and 42.2% relative to N4W3, respectively. This may lead to significant increase in EUE, WP, AEN and net income in N3W2. Furthermore, the CF, WF, and NF increased as the water and nitrogen input increased, whereas minimum CF, WF and NF per unit of yield was obtained N3/N4 or W1/W2 level. 240 kg N ha−1 coupled with 90–120 mm irrigation quota was recommended by TOPSIS for the HLSC-cultivated wheat to best trade-off resource use efficiencies, environmental footprints, and net benefits. Future studies are needed to further assess the scalability and adaptability of HLSC-cultivated wheat across different climatic zones and soil types.

Asymmetric Wettability Janus Mesh via Electrostatic Printing for Selective Oil-Water and Emulsion Separation.

Janus mesh with two-sided asymmetric wettability shows high potential for selective oil-water and emulsion separation. However, it remains a challenge to construct Janus mesh structures with good stability and extremely asymmetric wettability. Herein, a novel Janus mesh with asymmetric wettability was structured by two different precursors, polydimethylsiloxane/zinc oxide (PDMS/ZnO) and zinc oxide-polyacrylonitrile/N,N-dimethylformamide (ZnO-PAN/DMF), by electrostatic printing, including electrostatic air spraying and electrostatic spinning. The prepared Janus mesh has special micro-nanostructures on two sides, including PDMS@ZnO and ZnO@PAN. On the basis of gravity, when the placement direction is changed, Janus mesh can effectively separate oil-water mixtures of different densities and surfactant-stabilized oil-water emulsions. Meanwhile, the obtained Janus mesh exhibited good separation efficiency (>96.3%) for various oil-water mixtures, and the flux was up to 2621 ± 30 L m-2 h-1. The Janus mesh was cycled 20 times with no weakening in separation efficiency, indicating satisfactory cycling stability. The Janus mesh displayed good stability under harsh conditions (acidic, alkaline, and high temperature). The Janus mesh can realize low energy input and long-lasting oil-water separation, which has widespread application prospects in intelligent oil-water separation. This top-down electrostatic printing strategy provides a way to construct Janus interface materials with practical applications.

A sustainable bio-circular way for biorefinery of rice straw into bioproducts based on energy-efficient pretreatment

Lignocellulosic biorefinery faces challenges associated with high energy input during pretreatment and high enzyme cost for enzymatic hydrolysis of cellulose, as well as the intricate valorization of lignin and hemicellulose. This study applied KOH-urea pretreatment to obtain maximum lignin removal of 68.93 % from rice straw at 80 °C for 60 min. The pretreatment consumed only 10.49 % of the total energy input. Five-time dilution of neutral black liquor can optimally stimulate the plant growth. Enzymatic conversion of KOH-urea-treated rice straw attained 92.02 % at 20 % solid concentration with 10 FPU cellulase/g substrate. The ethanol concentration achieved 37.02 g/L at a yield of 75.89 %. The solid residue after fermentation contained 42.40 % dietary fiber and 16.70 % protein, which is suitable as animal feed. This study developed a simple bio-circular way to concurrently produce liquid fertilizer, bioethanol, and animal feed from rice straw.

Assessment and measurement of ground motion risk levels for structures isolated by double concave friction pendulum system

Determining the risk level of ground motions (GM) for structures is crucial for their damage control and resilience enhancement, while the assessment and measurement criteria of GM risk levels for structures isolated by double concave friction pendulum system (DCFPS) remain unclear. Through statistical analysis of the response distribution of DCFPS with various design parameters under 1013 GM records, this study determines an energy dissipation efficacy of 99 %, a floor velocity of 0.35 m/s, a floor velocity of 0.60 m/s, and the displacement capacity of DCFPS as the response criteria for assessing four performance states of efficacy, habitability, functionality, and safety, respectively. In addition, the value of GM intensity in PGA, PGV, PGD, and the equivalent velocity of seismic input energy (VE) for measuring the four GM risk levels corresponding to the four performance states are obtained. Furthermore, a classification of GMs based on earthquake magnitude and fault distance is proposed according to their risk to DCFPS. It is found that the intensity value of each GM risk level varies for different design parameters of DCFPS but fluctuate within a small range, however, great differences exist when using different intensity measures (IM) in classifying GM risk levels. Therefore, based on the correlation between IMs and DCFPS responses, the conservatism of PGA, PGV, PGD and VE in assessing the risk of GMs for DCFPS are evaluated.

Laser-beam powder bed fusion of magnetostrictive Fe81Ga19 alloys: parameter optimization, microstructural evolution and magnetostrictive properties

Magnetostrictive Fe-Ga alloys, featuring with good machinability, high Curie temperature, and high permeability, have received increasing attention in fields such as actuators, implants, and energy harvesting. Unfortunately, bulk polycrystalline Fe-Ga alloys usually suffer poor magnetostrictive strains compromised by the randomness of grain structure and the intricate phase constitution. The current study was centered on the fabrication of bulk polycrystalline Fe81Ga19 alloys with tailored grain morphology and phase arrangement utilizing laser-beam powder bed fusion (LPBF) technology. Particular emphasis was laid on investigating the repercussions of LPBF process parameters on the microstructure and magnetostrictive performance. The findings illustrated a non-linear interplay between laser power and the relative density of laser powder bed fusion-fabricated (LPBFed) Fe81Ga19 alloys, marked by an initial augmentation followed by a subsequent decrement. Similarly, a consistent trend was observed for the LPBFed alloys at varying scan speeds. In particular, the LPBFed Fe81Ga19 alloys exhibited a highest density at optimized process parameters (laser power set at 120 W paired with a scan speed of 100 mm s−1) due to suitable laser energy input during LPBF process. It was experimentally shown that elongated columnar grains and disorder A2 phase structures were obtained within the alloys attibutes to the high temperature gradient and rapid cooling kinetics intrinsic to LPBF, contributing to a desirable magnetostrictive strain of ∼87 ppm for bulk polycrystalline Fe81Ga19 alloys. Moreover, a good dynamic magnetostrictive response of the LPBFed alloys was confirmed by the near-synchronous variations between magnetostrictive behavior and alternating magnetic fields. It can be derived from these findings that LPBF process may be a promising method to prepare bulk magnetostrictive Fe-Ga alloys for versatile applications.

Experimental study and numerical simulation on porosity dependent direct reducibility of high-grade iron oxide pellets in hydrogen

The transition to more environmentally friendly steel production methods has intensified research into hydrogen-based direct reduction (HyDR) of iron oxide pellets. The aim of this study is to systematically investigate the kinetics of the reduction process, the evolution of porosity and the resulting microstructural changes on the reduction behavior of high-quality pellets during HyDR of iron ore at different temperatures. A modified mathematical model is developed based on the shrinkage kernel model, taking into account both mass and heat transport in a hydrogen atmosphere. The effects of temperature, particle size and time on the reduction behavior of the pellets are investigated. The simulated results are validated and discussed by the results of a batch of iron oxide pellets consisting of ten almost spherical pellets subjected to the direct reduction process with pure hydrogen. The results show that the total energy input to the HyDR process is a complex balance of factors, including chemical reaction rates, diffusion dynamics and entropy generation. The increase in free volume and simultaneous decrease in pore diameter reflect the dynamic nature of the microstructure, which includes additional free volume and defects due to the volume discrepancies and associated stresses between the reactant and product phases. Furthermore, the data show that higher temperatures accelerate the reduction reactions, especially the transformation of wustite into metallic iron. This phase transition is characterized by a significant volume change that cannot be accommodated by elastic deformation alone, leading to the development of lattice defects such as cracks, creep pores and dislocations that serve as stress relief mechanisms. The trends for porosity change at 950 °C and 1000 °C observed in the experimental results are correct and in good agreement with the numerical and simulated results.

Design, assembly and testing of an upgraded aeroacoustics wind tunnel facility

The Aeroacoustics Laboratory in the Department of Aerospace Engineering at Penn State currently serves several areas of experimental research. Most notable in the laboratory is the Anechoic Chamber of which the Aeroacoustics Wind Tunnel is an integral part. In recent years the dominant areas of research have included model aircraft exhaust jets and model rotors for helicopter applications involving detailed noise experiments. In the jet noise area, the applications have included aircraft in both flyover and take-off configurations. In the flyover application the air flow surrounding the exhaust jet has a significant effect on the radiated noise and must be simulated to produce experimental results that will be most useful in preliminary design of noise suppression applications. The Aeroacoustics Wind Tunnel at Penn State serves the purpose for this simulation. During aircraft take-off, the aircraft airspeed is in a range exceeding 250 ft per second, or Mach number of over M = 0.22. In the years preceding 2022, the velocity of the free jet flow of the Penn State facility was limited to less than 200 ft/sec. This paper reports on a project to design upgrades to the existing wind tunnel to improve the test section flow velocity to values closer to the 250 ft/sec target. The approach began with a preliminary design of the return flow ducting to convert the open jet, open return wind tunnel to a closed return tunnel. The concept is to make use of the flow energy in the exhaust of the tunnel to boost the input energy to the inlet fan that drives the flow to the test section. An integral part of the preliminary design involved making use of an upgraded flow analysis computer code to predict the gain in test section velocity of the new facility. For the available horsepower of two fans in the facility, the configurations of the existing and upgraded wind tunnel were entered into this analysis code based on a quasi-one-dimensional formulation. The code included empirical data formulated to include the various shapes of the components of the tunnels. The relative flow velocities in each section used simple incompressible continuity to calculate all velocities in the component sections. The average dynamic pressure in each section is calculated from the flow (constant) density and the velocity squared. Each section had a non-dimensional pressure loss parameter calculated from empirical data (from the relevant literature). The basic code (using the Excel algorithms) was based on a predictor-corrector concept in which the calculation was initialized with the estimated velocity and pressure of the flow at the entrance to the test section. The loss in each following section is estimated to determine the loss in the total pressure and the cumulated loss compared to the gains made at the two fans in the circuit. The initial guess is adjusted based on the total pressure value at the end of the circuit. During the related experiments, measurements of the total and dynamic pressure were performed at several joints between sections and compared to the values predicted in the analysis code. Various settings of the horsepower of the drive fans were used and the results were compared to flow measurements for the tunnel configurations (predominantly for the open return and closed return tunnel setups available before and after the upgrade project.) Results of the analysis and experiments are presented and analyzed together with the remaining activities planned for the coming months.

Homogenous Oxidizing Oligomerization Coupled with Coagulation for Water Purification

Natural manganese oxides could induce the intermolecular coupling reactions among small-molecule organics in aqueous environments, which is one of the fundamental processes contributing to natural humification. These processes could be simulated to design novel advanced oxidation technology for water purification. In this study, periodate (PI) was selected as the supplementary electron-acceptor for colloidal manganese oxides (Mn(IV)aq) to remove phenolic contaminants from water. By introducing polyferric sulfate (PFS) into the Mn(IV)aq/PI system and exploiting the flocculation potential of Mn(IV)aq, a post-coagulation process was triggered to eliminate soluble manganese after oxidation. Under acidic conditions, periodate exists in the H4IO6− form as an octahedral oxyacid capable of coordinating with Mn(IV)aq to form bidentate complexes or oligomers (Mn(IV)-PI*) as reactive oxidants. The Mn(IV)-PI* complex could induce cross-coupling process between phenolic contaminants, resulting in the formation of oligomerized products ranging from dimers to hexamers. These oligomerized products participate in the coagulation process and become stored within the nascent floc due to their catenulate nature and strong hydrophobicity. Through coordination between Mn(IV)aq and H4IO6−, residual periodate is firmly connected with manganese oxides in the floc after coagulation and could be simultaneously separated from the aqueous phase. This study achieves oxidizing oligomerization through a homogeneous process under mild conditions without additional energy input or heterogeneous catalyst preparation. Compared to traditional mineralization-driven oxidation techniques, the proposed novel cascade processes realize transformation, convergence, and separation of phenolic contaminants with high oxidant utilization efficiency for low-carbon purification.

Peristome‐mimetic Surfaces Fabricated by Nanosecond Laser for Uni‐directional Liquid Spreading

Unidirectional liquid transport, which operates without external energy input, has garnered remarkable interests in the global energy sector. A crucial breakthrough in this field involves understanding how liquids spread on the peristome surface of Nepenthes alata. This study, inspired by the microstructural traits of the Nepenthes peristome, has brought about the development of a biomimetic surface on metal substrates using nanosecond laser processing on inclined bases. This process replicates the natural peristome’s microstructure, which allows for controlled liquid spread on the surface. The research also examines how wettability influences unidirectional liquid spread. Additionally, it involves adjusting the microstructure parameters on the biomimetic surface, which leads to variations in edge curvature and microcavity wedge angles. More importantly, this study comprehensively investigates the relationship between these structural changes and the phenomenon of unidirectional liquid transport. The findings suggest that altering edge curvature and micro‐cavity wedge angles can manage the directional spread of liquids. The optimized surface, with ideal curvature and wedge angles, achieves liquid movement speeds up to 12.03mm/s. This represents a notable improvement, 2.2 and 2.7 times faster than the original structure, respectively. These findings provides valuable insight into the design of energy‐independent unidirectional liquid spreading surfaces on metal substrates.This article is protected by copyright. All rights reserved.

A Semi-Interpenetrating Network Sorbent of Superior Efficiency for Atmospheric Water Harvesting and Solar-Regenerated Release.

Water is readily available nearly anywhere as vapor. Thus, atmospheric water harvesting (AWH) technologies are seen as a promising solution to support sustainable water production. This work reports a novel semi-interpenetrating network, which integrates poly(pyrrole) doped with a hygroscopic salt and 2D graphene-based nanosheets optimally assembled within an alginate matrix, capable of harvesting water from the atmosphere with a record intake of up to 7.15 gw/gs. Owing to the incorporated graphene nanosheets, natural sunlight was solely used to enable desorption, achieving an increase of the temperature of the developed network of up to 71 °C within 20 min, resulting in a water yield of 3.36 L/kgS in each cycle with quality well within the World Health Organization standard ranges. Notably, after 30 cycles of sorption and desorption, the composite hydrogel displayed unchanged water uptake and stability. This study demonstrates that atmospheric water vapor as a complementary source of water can be harvested sustainably and effectively at a minimal cost and without external energy input.

Designing Pathway-Controlled Multicomponent Ultrashort Peptide Hydrogels with Diverse Functionalities at the Nanoscale for Directing Cellular Behavior.

Tuning self-assembling pathways by implementing different external stimuli has been extensively studied, owing to their effective control over structural and mechanical properties. Consequently, multicomponent peptide hydrogels with high structural tunability and stimuli responsiveness are crucial in dictating cellular behavior. Herein, we have implemented both coassembly approach and pathway-dependent self-assembly to design nonequilibrium nanostructures to understand the thermodynamic and kinetic aspects of peptide self-assembly toward controlling cellular response. Our system involved an ultrashort peptide gelator and a hydrophilic surfactant which coassembled through different pathways, i.e., heat-cool and sonication methods with variable energy input. Interestingly, it was possible to access diverse structural and mechanical properties at the nanoscale in a single coassembled system. Further, the hydrophilic surfactant provided additional surface functionalities, thus creating an efficient hydrophilic matrix for cellular interaction. Such diverse functionalities in a single coassembled system could lead to the development of advanced scaffolds, with applications in various biomedical fields.

Effect of Janus nanoparticles on foam snap off in porous media

Abstract Nanoparticles can be adsorbed at the gas-liquid interface to improve the stability of foam. However, homogeneous nanoparticles exhibit low surface activity, and their migration to the gas-liquid interface requires significant energy input. This leads to harsh foaming conditions and severely limits the application of homogeneous nanoparticles in foam stability. A microfluidic visualisation model for the study of Janus nanoparticle complex systems was used to investigate the formation behaviour of trapped bubbles in a single connected pore-throat model. The foam generated in the pore showed reduced quantities, sizes, improved quality, and enhanced stability compared to both surfactant systems and hydrophilic nanoparticle complex systems.

Near-inertial response of a salinity-stratified ocean

Abstract We study the near-inertial response of the salinity-stratified north Bay of Bengal to monsoonal wind forcing using six years of hourly observations from four moorings. The mean annual energy input from surface winds to near-inertial mixed-layer currents is 10–20 kJ/m2, occurring mainly in distinct synoptic “events” from April to September. A total of fifteen events are analyzed: Seven when the ocean is capped by a thin layer of low-salinity river water (fresh) and eight when it is not (salty). The average near-inertial energy input from winds is 40% higher in the fresh cases than in the salty cases. During the fresh events, (A) mixed layer near-inertial motions decay about two times faster, and (B) near-inertial kinetic energy below the mixed layer is reduced by at least a factor of three relative to the salty cases. The near-inertial horizontal wavelength was measured for one fresh and one salty event; the fresh was about three times shorter initially. A linear model of near-inertial wave propagation tuned to these data reproduces (B); the thin (10 m) mixed layers during the fresh events excite high modes, which propagate more slowly than the low modes excited by the thicker (40 m) mixed layers in the salty events. The model does not reproduce (A); the rapid decay of the mixed layer inertial motions in the fresh events is not explained by linear wave propagation at the resolved scales; a different and currently unknown set of processes is likely responsible.

Short-term behavioral and histological findings following a single concussive and repeated subconcussive brain injury in a rodent model

ABSTRACT Primary Objective It is unclear of the correlation between a mild traumatic brain injury (mTBI) and repeated subconcussive (RSC) impacts with respect to injury biomechanics. Thus, the present study was designed to determine the behavioral and histological differences between a single mTBI impact and RSC impacts with subdivided cumulative kinetic energies of the single mTBI impact. Research Design Adult male Sprague-Dawley rats were randomly assigned to a single mTBI impact, RSC impact, sham, or repeated sham groups. Methods and Procedures Following a weight drop injury, anxiety-like behavior and general locomotive activity and were assessed using the open field test, while motor coordination was evaluated using a rotarod unit. Neuronal loss, astrogliosis, and microgliosis were assessed using NeuN, GFAP and Iba-1 immunohistochemistry. All assessments were undertaken at 3- and 7-days post impact. Main Outcomes and Results No behavioral disturbances were observed in injury groups, however, both injury groups did lead to microgliosis following 3-days post-impact. Conclusions No pathophysiological differences were observed between a single mTBI impact and RSC impacts of the same energy input. Even though a cumulative injury threshold for RSC impacts was not determined, a threshold still may exist where no pathodynamic shift occurs.

Triaxial behavior of unreinforced and geogrid-reinforced calcareous gravelly sand: Experiment and discrete element modelling

Geogrid reinforcement is a feasible technique for improving the mechanical and deformation behaviors of calcareous gravelly sand that is predominantly distributed in reclaimed foundations as construction materials. However, the shear behavior of geogrid-reinforced calcareous gravelly sand still remains unclear. In this paper, a series of large-scale drained consolidated triaxial compression tests (the specimen 300 mm in diameter by 600 mm in height) were conducted to investigate the effects of confining pressure, moisture content and geogrid inclusion on the mechanical and deformation behaviors of calcareous gravelly sand. The dilation effect, strain-softening behavior, reinforcing effect and particle breakage characteristics of unreinforced and geogrid-reinforced calcareous gravelly sand were comprehensively analyzed and discussed. Additional analysis was also performed from a microscopic perspective using the three-dimensional discrete numerical modelling. The experimental results indicate that calcareous gravelly sand exhibited a greater resistance to strain-softening tendency, and produced a higher susceptibility to crushing under the same input energy than calcareous coarse sand. Geogrid inclusion can effectively mitigate the susceptibility of calcareous gravelly sand to volumetric dilation through constraining the lateral expansion within the reinforced zone, and thus substantially increased the peak shear strength. Moreover, particle breakage appeared to be insensitive to geogrid reinforcement and water content, but increased significantly with increasing confining pressures. The numerical results further indicate that the mechanical response of geogrids was regulated by axial strain and confining pressure. As axial strain was greater than 10%, increased confining pressure resulted in a wider area of stress concentration within the geogrid meshes, and the upper geogrid sustained a greater contact force and tensile strain. The findings in this study are of practical significance for the design and construction of structures in calcareous gravelly sand reinforced with geogrids.

On the intrinsic recycling potential of carbon-based materials and products; an assessment method and outlook

In this paper we investigate the market size of all materials and products presently produced from (organic) carbon and we present a method to estimate the intrinsic recycling potential of these materials/chemicals as a function of their respective applications. The method is based on the expert assessment of a number of variables that are important within the different application categories and markets of the carbon-based materials/chemicals. Applying the method, the paper presents the recycling potential of all carbon-based products. Following, an estimation of the amount of new products that can be produced each year through recycling of discarded products is presented and the amount of carbon that needs to come from other sustainable sources to fulfil our demand for new products is calculated.We distinguish nine different categories of (organic) carbon-based materials/chemicals: plastics, textile fibres, thermoset resins, rubbers, surfactants, solvents, fine chemicals, paper/board and wood products. Within these nine categories the most important materials/chemicals types were taken into account. Fossil-based and bio-based materials/chemicals were assessed separately. For each of the materials/chemicals types, the market size in terms of mass (Mt) was calculated for the main applications in which they are applied. Next, for all materials/chemicals types in these applications, the maximum recycling potential, in case mechanical or physical recycling methods are applied, was assessed, using an expert panel. Also, inevitable leakage of materials/chemicals in the different applications was assessed. Finally, the amount of feedstock coming from recycling streams that may be made available for chemical recycling or carbon capture and utilisation technologies was derived. From this, the magnitude of carbon-based materials/chemicals that need to be replaced each year by other renewable feedstock than recycled content in terms of Mton carbon was calculated.The analysis is relevant in view of implementation of a circular economy and reuse and recycling of materials, to combat depletion of raw materials. Next, it is relevant in view of phasing out fossil-feedstock to combat climate change. Our analysis indicates that the recycling potential of carbon-based materials and products through mechanical or physical methods lies around 50%, even in a system that is fully optimised for recycling. Chemical recycling and carbon capture and utilisation may provide another 25% of the renewable-carbon feedstock needed, but they generally require far more energy and other inputs to produce new materials and chemicals than the mechanical and physical recycling methods. The remaining demand for renewable-carbon feedstock thus needs to come from either biomass or CO2 through carbon capture and utilisation technologies. Based on our findings, we argue that the composition of our present carbon-based products pool needs to be redesigned on a fundamental molecular level, towards material types that contain more oxygen. Carbon-based materials that contain more oxygen generally can be recycled more efficiently, and are also easier to produce from the alternative feedstocks biomass and CO2 through CCU.

Conversions and selectivities in cold plasma partial oxidation of methane

AbstractIn the present work, the application of dielectric barrier discharge (DBD) cold plasma technology for the partial oxidation of methane was systematically studied. Conversion of the reactants and selectivities were measured using an elaborate product analysis from a recent work by Müller et al. varying the reactant ratio in the feed, the mole fraction of the inert carrier gas argon in the feed, and the specific energy input at operating conditions close to ambient. The results from 20 new experiments carried out in the present work complement 23 previous experiments and provide an unprecedented comprehensive quantitative data set. This extends the available knowledge of partial oxidation of methane in DBD cold plasma considerably and is useful for testing mechanistic models.