Solid Interior Research Articles

A long section of serpentinized depleted mantle peridotite.

The upper mantle is critical for our understanding of terrestrial magmatism, crust formation, and element cycling between Earth's solid interior, hydrosphere, atmosphere, and biosphere. Mantle composition and evolution have been primarily inferred by surface sampling and indirect methods. We recovered a long (1268-meter) section of serpentinized abyssal mantle peridotite interleaved with thin gabbroic intrusions. We find depleted compositions with notable variations in mantle mineralogy controlled by melt flow. Dunite zones have predominantly intermediate dips, in contrast to the originally steep mantle fabrics, indicative of oblique melt transport. Extensive hydrothermal fluid-rock interaction is recorded across the full depth of the core and is overprinted by oxidation in the upper 200 meters. Alteration patterns are consistent with vent fluid composition in the nearby Lost City hydrothermal field.

Seasonal Variations in Radon and Thoron Exhalation Rates from Solid Concrete Interior Walls Observed Using In Situ Measurements

Building materials, such as brick and concrete, are known indoor radon (222Rn) and thoron (220Rn) sources. Most radon and thoron exhalation studies are based on the laboratory testing of pieces and blocks of such materials. To discuss if laboratory findings can be applied to a real-world environment, we conducted intensive in situ exhalation tests on two solid concrete interior walls of an apartment in Japan for over a year. Exhalation rates of radon (JRn) and thoron (JTn) were measured using an accumulation chamber and dedicated monitors, alongside monitoring indoor air temperature (T) and absolute humidity (AHin). There were weak correlations between JRn or JTn and T or AHin at one tested wall, and moderate correlations of JRn and strong correlations of JTn with T or AHin at the other wall, meaning more or less seasonal variations. The findings aligned with previous laboratory experiments on JRn but lacked corresponding data for JTn. Additionally, a moderate or strong correlation between JRn and JTn was observed for both tested walls. Comparison with theoretical calculations revealed a new issue regarding the impact of each process of emanation and migration within concrete pores on radon and thoron exhalation. Overall, this study provides insight into parameterizing radon and thoron source inputs in modeling the spatiotemporal dynamics of indoor radon and thoron.

Thermal tides in neutrally stratified atmospheres: Revisiting the Earth’s Precambrian rotational equilibrium

Rotational dynamics of the Earth, over geological timescales, have profoundly affected local and global climatic evolution, probably contributing to the evolution of life. To better retrieve the Earth’s rotational history, and motivated by the published hypothesis of a stabilized length of day during the Precambrian, we examined the effect of thermal tides on the evolution of planetary rotational motion. The hypothesized scenario is contingent upon encountering a resonance in atmospheric Lamb waves, whereby an amplified thermotidal torque cancels out the opposing torque generated by the oceans and solid interior, driving the Earth into rotational equilibrium. With this scenario in mind, we constructed an ab initio model of thermal tides on rocky planets describing a neutrally stratified atmosphere. The model takes into account dissipative processes with Newtonian cooling and diffusive processes in the planetary boundary layer. We retrieved, from this model, a closed-form solution for the frequency-dependent tidal torque, which captures the main spectral features previously computed using 3D general circulation models. In particular, under longwave heating, diffusive processes near the surface and the delayed thermal response of the ground prove to be responsible for attenuating, and possibly annihilating, the accelerating effect of the thermotidal torque at the resonance. When applied to the Earth, our model prediction suggests the occurrence of the Lamb resonance in the Phanerozoic, but with an amplitude that is insufficient for the rotational equilibrium. Interestingly, though our study was motivated by the Earth’s history, the generic tidal solution can be straightforwardly and efficiently applied in exoplanetary settings.

Quenching extinction of solid sphere diffusion flames induced by a sudden removal of gravity

The response of a diffusion flame around a PMMA solid sphere to a sudden transition to zero-gravity is investigated both experimentally and numerically. The initial flame is established in normal gravity with a low speed forced flow in a 17% oxygen by volume atmosphere. An abrupt (step change) normal-to-zero gravity transition occurs when the test package is released in the drop tower. The dynamic flame response is recorded by video and modeled numerically. By the end of the 5.18-s drop, the flame tip retreats, and the flame base may either remain stabilized near the forward stagnation region or extinguish depending on several parameters. The two parameters investigated are: forced flow velocity and the degree of preheating in the surface layer of the solid sample. The amount of preheating or equivalently the conductive flame heat loss rate to the solid interior is varied by controlling the duration of the normal gravity burning before releasing to microgravity. The heat loss is quantified by using embedded thermocouples to measure the solid subsurface temperature gradient near the stagnation point. The detailed numerical model reveals details of the flow field and flame structure including oscillatory extinction and quantifies the various transient gas-solid surface energy balance terms.

Spherical and porous Cu2O nanocages with Cu2O/Cu(OH)2 Surface: Synthesis and their promising selectivity for catalysing CO2 electroreduction to C2H4

In the production of C2H4, a vital raw material in the synthesis of polyethylene and polyvinyl chloride, Cu2O is a highly promising catalyst with excellent Faradaic efficiency and selectivity. We propose a method involving the partial reduction of Cu(OH)2 to Cu2O by sodium L-ascorbate for the synthesis of spherical and porous Cu2O nanocages (SPNCs) with a surface containing both Cu2O and Cu(OH)2. High-resolution transmission electron microscopy and electron diffraction measurements revealed ∼ 3-nm pores and a (13¯2) high-index facet on the SPNC, respectively. As SPNCs have a porous structure, their specific surface area is greater (31.10 m2 g−1) than that (6.35 m2 g−1) of spherical Cu2O nanocrystals (SNCs) with solid interiors. Furthermore, SPNCs, when applied as electrocatalysts for catalysing the CO2 reduction reaction (CO2RR), demonstrated remarkable mass activities (16.92 mA mg−1 at −1.15 V vs. reversible hydrogen electrode) for C2H4 production, with a Faraday efficiency reaching an impressive 55.3 %. Stability test data showed a consistent CO2RR current density over 6 h, owing to the porous structure and the presence of both Cu(OH)2 and Cu2O on the catalyst surface. Our proposed SPNC catalysts can be employed as effective CO2RR catalysts for producing C2H4, which may help in reducing the present reliance on petrochemical processes.

Numerical Analysis of Textile Reinforced Concrete Shells: Force Interaction and Failure Types

In the case of solid slabs made of reinforced concrete that are usually subjected to bending, large areas of the structure are stressed well below their load-bearing capacity. Contrary to this are shell structures, which can bridge large spans with little material if designed according to the force flow. To improve the efficiency of ceiling slabs, we want to utilize the shell load-bearing behavior on a smaller scale by resolving the solid interior accordingly. In order to study a wide range of such constructions virtually, a parametric multi-objective simulation environment is being developed in an ongoing research project. The basic analysis approaches that were implemented are presented in this paper. The basic workflow, the used programs and material models, and their calibration on the tests on textile-reinforced concrete (TRC) samples are described.

The Numerical Analysis of Textile Reinforced Concrete Shells: Basic Principles

In the case of solid slabs made from reinforced concrete that are usually subjected to bending, large areas of the structure are stressed well below their load-bearing capacity or remain stress-free. Contrary to this are shell structures, which can bridge large spans with little material if designed well. To improve the efficiency of ceiling slabs, we want to utilize the shell load-bearing behaviour on a smaller scale by dissolving the solid interior accordingly. In order to be able to study a wide range of such constructions virtually, a parametric multi-objective simulation environment is to be developed in an ongoing research project, the basic analysis approaches of which are presented in this paper. In addition to the basic workflow and the programs used, the material models for TRC material compared and their calibration are described on the basis of tests on textile reinforced concrete (TRC) samples. Various material models were implemented within the commercially available software RFEM (Version 5.19). Laboratory tests on two different geometry solutions of TRC structures served to verify the models. The structures were selected in a way that differentiates between the bending and membrane actions to indicate the application fields for various approaches in the numerical modelling of TRC structures.

Sublithospheric Diamonds: Plate Tectonics from Earth's Deepest Mantle Samples

Sublithospheric diamonds and the inclusions they may carry crystallize in the asthenosphere, transition zone, or uppermost lower mantle (from 300 to ∼800 km), and are the deepest minerals so far recognized to form by plate tectonics. These diamonds are distinctive in their deformation features, low nitrogen content, and inclusions of these major mantle minerals: majoritic garnet, clinopyroxene, ringwoodite, CaSi perovskite, ferropericlase, and bridgmanite or their retrograde equivalents. The stable isotopic compositions of elements within these diamonds (δ11B, δ13C, δ15N) and their inclusions (δ18O, δ56Fe) are typically well outside normal mantle ranges, showing that these elements were either organic (C) or modified by seawater alteration (B, O, Fe) at relatively low temperatures. Metamorphic minerals in cold slabs are effective hosts that transport C as CO3 and H as H2O, OH, or CH4 below the island arc and mantle wedge. Warming of the slab generates carbonatitic melts, supercritical aqueous fluids, or metallic liquids, forming three types of sublithospheric diamonds. Diamond crystallization occurs by movement and reduction of mobile fluids as they pass through host mantle via fractures—a process that creates chemical heterogeneity and may promote deep focus earthquakes. Geobarometry of majoritic garnet inclusions and diamond ages suggest upward transport, perhaps to the base of mantle lithosphere. From there, diamonds are carried to Earth's surface by eruptions of kimberlite magma. Mineral assemblages in sublithospheric diamonds directly trace Earth's deep volatile cycle, demonstrating how the hydrosphere of a rocky planet can connect to its solid interior. ▪Sublithospheric diamonds from the deep upper mantle, transition zone, and lower mantle host Earth's deepest obtainable mineral samples.▪Low-temperature seawater alteration of the ocean floor captures organic and inorganic carbon at the surface eventually to become some of the most precious gem diamonds.▪Subduction transports fluids in metamorphic minerals to great depth. Fluids released by slab heating migrate, react with host mantle to induce diamond crystallization, and may trigger earthquakes.▪Sublithospheric diamonds are powerful tracers of subduction—a plate tectonic process that deeply recycles part of Earth's planetary volatile budget.

Efficiency enhancement and application of laser ultrasonic longitudinal wave based on glass constraint

Due to the weak longitudinal signals generated by laser ultrasound in the thermoelastic mechanism, the characteristic echoes are weak when evaluating the interior of solids, thus limiting its application to internal defect detection. A glass confinement layer is introduced to enhance the longitudinal excitation effectiveness. Specially, a thermoelastic model of laser ultrasound with a glass confinement is established to explain the mechanism of the enhancement of the longitudinal wave effectiveness, and the effect of the glass width on the longitudinal wave generated by the base ultrasound is investigated. The effect of the glass confinement layer on the enhancement of the effectiveness of the internal defects detection is studied. The simulation and experimental results show that the longitudinal waves with high signal-to-noise ratio induced from thermoelastic effect are excited similar to the ablation mechanism, which greatly improves the excitation efficiency of the longitudinal waves. The deep detection defects and the accurate localization of depth information are realized with an error of no more than 1.2%.

Spin–orbit coupling of Europa’s ice shell and interior

Europa is an icy ocean world, differentiated into a floating ice shell and solid interior, separated by a global ocean. The classical spin–orbit coupling problem considers a satellite as a single rigid body, but in the case of Europa, the existence of the subsurface ocean enables independent motion of the ice shell and solid interior. This paper explores the spin–orbit coupling problem for Europa from a dynamical perspective, yielding illuminating analytical and numerical results. We determine that the spin behavior of Europa is influenced by processes not captured by the classical single rigid body spin–orbit coupling analysis. The tidal locking process for Europa is governed by the strength of gravity-gradient coupling between the ice shell and solid interior, with qualitatively different behavior depending on the scale of this effect. In this coupled rigid model, the shell can potentially undergo large angular displacements from the solid interior, and the coupling plays an outsize role in the dynamical evolution of the moon, even without incorporating the dissipative effects of shell non-rigidity. We additionally discuss the effects of a realistic viscoelastic shell, and catalogue other torques that we expect to be sub-dominant in Europa’s spin dynamics, or whose importance is unknown. Finally, we explore how the choice of tidal model affects the resulting equilibrium spin state.

Direct Recycling and Upcycling of Spent Graphite Anodes

Lithium-ion batteries (LIBs) have emerged as the battery of choice for rapidly growing markets in electric vehicles (EVs) and energy storage devices. Thus, there is an enormous interest in the development of new technologies for recycling and recovery of valuable materials from secondary resources, such as those from used LIBs. Finding ways to decrease the cost of recycling could significantly reduce the life cycle cost of LIBs, avoid material shortages, lessen the environmental impact of new material production, and provide low-cost active materials for new LIB manufacturing. The recycling of spent LIBs has mainly been focused on the recycling of the cathode, while recycling of the graphite anode has only received limited attention due to its low value and complex recycling process. However, with the recent shortage of resources and the increase in production costs, recycling of the graphite anode from spent batteries can no longer be ignored. There are several challenges associated with recovering spent graphite anodes – mainly, there are a variety of metal impurities in addition to surface impurities from the solid electrolyte interface (SEI) and interior impurities that need to be removed. Conventional recycling methods are unable to solve this issue, especially for the purification process. Most current recycling systems use pyrometallurgical and/or hydrometallurgical methods, which necessitate multi-unit operations, high energy consumption, and high cost. Direct recycling, on the other hand, is a promising solution for overcoming the hurdles involved with recovering spent graphite anodes.Princeton NuEnergy (PNE) has successfully developed a novel low-temperature plasma process to enable purification and direct repair of graphite anode materials from spent LIBs. We also demonstrated a simple but effective surface coating approach to upgrade the spent graphite to produce a graphite-silicon composite that has an improved energy density. Spent graphite is an ideal choice for low-cost production of high-performance silicon-graphite composites because treated spent graphite presents a porous structure that can be combined well with silicon and effectively relieve volume expansion. The recycled graphite and upcycled graphite-silicon composite anode materials outperform the commercially available equivalent materials. The direct recycling/upcycling of graphite anode materials will increase the commercial viability of LIBs and reduce battery cost, thus accelerating the electrification of transportation and large-scale energy storage for renewable energy in the near future. In this presentation, the materials characterization and electrochemical performance of recycled/upcycled anode materials will be discussed.BEK and CY acknowledge support of this research by Princeton University under the Intellectual Property Accelerator Fund.

Large scale synthesis of carbon nanopearl chains by chemical vapor deposition

We report the synthesis of a novel type of carbon-based nanostructure, which is composed of a string of carbon nanopearl chains (CNPCs) with a connection structure of carbon nanofibers using a chemical vapor deposition method. Regularly spaced, nanometer-sized balls of graphitic carbon are found on the amorphous nanofibers. The nanopearls have nanometer-sized spheres, bodies in diameter varying from tens of nanometers to hundreds of nanometers, with solid interiors. The chain connections have a length ranging from several nanometers up to micrometers between two nanopearls. The nanopearls connect each other by the nanofibers, thus forming a chain. The CNPCs have potential for use as reinforcing matrix to produce strong and tough carbon-based nanocomposites.

Waterworlds May Have Better Climate Buffering Capacities than Their Continental Counterparts

Abstract The long-term habitability of a planet is often assumed to be controlled by its ability to cycle carbon between the solid planetary interior and atmosphere. This process allows the planet to respond to external forcings (i.e., changes in insolation, changes in volcanic outgassing rates, etc.) and regulate its surface temperature through negative feedbacks on atmospheric CO2 involved in silicate weathering. Continental weathering and seafloor weathering rates have different, non-linear dependencies on pCO2 and will respond differently to changes in external forcings. Because waterworlds (planets with only seafloor weathering) have a weaker pCO2 dependence than continental worlds (such as modern Earth), we find that waterworlds are better at resisting changes in surface temperature resulting from perturbations in insolation than their continental counterparts, and may be more habitable in this respect.

Snow lines can be thermally unstable

ABSTRACT Volatile species in protoplanetary discs can undergo a phase change from vapour to solid. These ‘snow lines’ can play vital roles in planet formation at all scales, from dust coagulation to planetary migration. In the outer regions of protoplanetary discs, the temperature profile is set by the absorption of reprocessed stellar light by the solids. Further, the temperature profile sets the distribution of solids through sublimation and condensation at various snow lines. Hence, the snow line position depends on the temperature profile and vice versa. We show that this coupling can be thermally unstable, such that a patch of the disc at a snow line will produce either runaway sublimation or condensation. This thermal instability arises at moderate optical depths, where heating by absorption of reprocessed stellar light from the disc’s atmosphere is optically thick, yet cooling is optically thin. Since volatiles in the solid phase drift much faster than volatiles in the vapour phase, this thermal instability results in a limit cycle. The snow line progressively moves in, condensing volatiles, before receding, as the volatiles sublimate. Using numerical simulations, we study the evolution of the carbon monoxide (CO) snow line. We find the CO snow line is thermally unstable under typical disc conditions and evolves inwards from ∼50 to ∼30 au on time-scales from 1000 to 10 000 yr. The CO snow line spends between ${\sim}10{{\ \rm per\ cent}}\,\mathrm{ and}\,50{{\ \rm per\ cent}}$ of its time at smaller separations, where the exact value is sensitive to the total opacity and turbulent viscosity. The evolving snow line also creates ring-like structures in the solid distribution interior to the snow line. Multiple ring-like structures created by moving snow lines could potentially explain the substructures seen in many ALMA images.

Synthesis, characterization and growth mechanism of carbon nanopears

We report a novel carbon morphology that we name “carbon nanopears” using chemical vapor deposition in the presence of silicon wafer as a substrate coating Ni catalyst, thiophene as the growth promoter and benzene as carbon source. The carbon nanopears observed under optimized experimental conditions have nanometer-sized sharp tips, nanometer-sized roots and solid interiors. The carbon nanopears are composed of graphitized carbon and amorphous carbon, with continuous shortening of the length of graphitic sheets from the exterior to interior making them pear-shaped. Furthermore, a probable CNP formation mechanism is proposed in this paper.

A Review on the Secondary Surface Morphology of Electrospun Nanofibers: Formation Mechanisms, Characterizations, and Applications

AbstractEngineering the secondary surface morphology of fibers (fibers without smooth surface and solid interior) has been attracting significant awareness in various areas and applications. Among different methods of forming nanofibers, electrospinning is the most widely adopted technique due to the ease of forming fibers with a broad range of properties and its unique advantages such as the flexibility to spin into a variety of shapes and sizes as well as adjustable porosity of electrospun structures. In this review paper, more emphasis is put on the secondary surface morphology. A comprehensive overview of the basic principles about the electrospinning process, types of electrospinning, materials, formation mechanisms, characterizations, and applications of electrospun fibers with the secondary surface morphology (e. g. the porous structure, grooved structure, wrinkled structure, rough structure, cactus structure, and hollow structure) are discussed in detail. Importantly, we believe our work can serve as guidelines for the preparations, characterizations, and applications of electrospun fibers with the secondary surface morphology.

Optimizing Design Patterns for Multi-Head Fused Deposition Modeling (FDM) Systems

This research examined various factors that affect successful FDM-type 3D printing. Specifically diameters of the nozzles, extrusion width, and layer thickness were varied to create several print patterns and fills. These print patterns were tested for appearance/surface finish, strength, speed and stiffness of composite materials and then the best print parameters and methodologies were recorded. The solid interior pattern fill showed the highest volume fill available, representing fewer voids and thus better strengths and more durable parts. The solid interior pattern fill also had the best surface finish for all types of fill. Also, printing with small layer thickness produced stronger prints albeit at higher build times.

Carbon paper with attached hollow mesoporous nickel oxide microspheres as a sulfur-hosting material for rechargeable lithium-sulfur batteries

Hollow nickel hydroxide microspheres built of nanosheets could be obtained by hydrothermal synthesis in the presence of glycine. After heating to 400 °C in air, the hexagonal β-Ni(OH)2 was converted into cubic NiO which showed better electrical conductivity and greater surface area compared with other annealing temperatures. The surface morphology remained almost unchanged, while the Ni(OH)2 nanosheets with solid interior were changed into NiO nanosheets composed of interconnected nanoparticles and mesopores after annealing at 400 °C. The sulfur-filled hollow mesoporous NiO microspheres obtained after annealing at 400 °C was loaded into the carbon paper as cathode (NiO/S) for lithium-sulfur batteries. The NiO/S cathode could deliver a large specific capacity of 1300 mAh g−1 at 0.2C (335 mA g−1), much greater than bare sulfur loaded into the carbon paper (1000 mAh g−1). Moreover, the NiO/S cathode showed superior capacity recovery after C-rate test and coulombic efficiency during cycling test than S cathode. The improved performance for NiO/S could be attributed to the conductive NiO microspheres with mesoporous nanosheets that provided intimate electrical contact for boosting the charge-transfer reaction between lithium ions and sulfur materials, limited the polysulfide shuttle, and buffered volumetric expansion/contraction during charging and discharging.

Structure-controlled synthesis of one-dimensional PdCu nanoscatalysts via a seed-mediated approach for oxygen reduction reaction

Herein, we introduce a facile strategy for the structure-controlled synthesis of one-dimensional PdCu nanocrystals via a seed-mediated approach. This developed strategy involves the synthesis of Cu nanowires with penta-twinned structure, and subsequent growth of Pd metal on Cu nanowires. The obtained one-dimensional PdCu nanocrystals are of rough surfaces and core-shell like architecture. Upon the tuning reactivity of (111) and (100) crystal faces on Cu nanowires in absence or presence of capping agent, one-dimensional PdCu nanocrystals with solid or hollow interiors (nanowires or nanotubes) can be controllably synthesized through galvanic displacement reaction, respectively. It is found that both PdCu nanowires and PdCu nanotubes exhibit better performance for oxygen reduction reaction compared with self-synthesized PdCu nanoparticles and commercial Pd/C in 0.1 M KOH electrolyte. Particularly, PdCu nanotubes show Pt-like performance, and achieve an onset potential of 0.941 V (vs. RHE) and a half potential of 0.825 V. The electron transfer number during oxygen reduction is close to 4 on PdCu nanotubes. Moreover, the catalytic stability of the obtained one-dimensional PdCu nanocrystals is much superior to that of commercial Pd/C and Pt/C catalysts.

Flame Growth Around a Spherical Solid Fuel in Low Speed Forced Flow in Microgravity

To further our understanding of flammability and quenching limit of thick solid fuels, a microgravity experiment Growth and Extinction Limits is to be conducted aboard the International Space Station with the emphasis to quantify the effect of the flame heat loss to the thermally thick solid interior by directly measuring the sub-surface temperature gradient. A precursor microgravity combustion experiment in the Burning and Suppression of Solids (BASS) project was used to assess the experimental operation and validate the accompanied numerical model. The present paper reports the development of the flame model over a solid sphere in low-speed pure convective flow (less than 100 cm/s). Computed time sequence result of one of the BASS conditions is presented. The combination of gas phase reaction rate, solid internal temperature and surface heat flux distribution reveals the effect of solid in-depth heat-up on flame growth. The experimental observations agree with the trend predicted by the model. For thick solids, flame quenching limit in low speed flow is not only a function of flow speed but also the degree of solid interior heat-up. Flammability limit can have profound implication to the current spacecraft fire protection protocol that requires turning-off of circulation flow in case of detected fire. The present and the follow-up studies will provide more quantitative estimate of the low velocity-quenching limit with heated samples. For the Polymethylmethacrylate spheres investigated, the limit is lower than 2 cm/s in air.