Void Structure Research Articles

Non-Fickian solute transport in three-dimensional crossed shear rock fractures at different contact ratios

Solute transport in fractured rocks plays a crucial role in many subsurface processes, such as geothermal resource extraction and carbon capture and storage. This study conducted simulations of non-Fickian solute transport at varying contact ratios and voids in crossed shear fractures. Results indicated that increasing the contact ratio of the crossed fractures intensified the “tailing” phenomenon of non-Fickian solute transport, and has a negative relationship with the solute outflow concentration. Additionally, the anisotropy of intersections and the variations in their void structure both influence the redistribution and mixing of fluid and solute, therefore, we propose a method to determine the solute mixing patterns at the intersection. Ultimately, while the volume and magnitude of the separated vortex domain in the flow field can influence the non-Fickian solute transport, the “tailing” phenomenon is more significantly affected by its magnitude.

Total Ionizing Dose Hardening of Planar SOI MOSFET Through an Optimal Design Combining Embedded Void and H-Gate Structures

Total Ionizing Dose Hardening of Planar SOI MOSFET Through an Optimal Design Combining Embedded Void and H-Gate Structures

Development of Pervious Paver Block Using Sugarcane Bagasse Ash & RAP Aggregates

Abstract: This particular kind of concrete is distinguished by its interconnected pore structure and significant void content or porosity, which typically varies from 15 to 35% by volume. Pervious concrete may lower the danger of flooding, diminish stormwater runoff, reduce noise when in contact with automobile tires, and avoid glare and skidding during rainy seasons by allowing water to easily infiltrate through its pores and replenish the ground water table. Considering the condition of the neighboring roadways, a modest effort is undertaken to construct the least amount of porous paver concrete. For the planned Mix proportions, compression strength, void ratio, and infiltration tests were conducted. In the current study, 60mm thick pervious paver blocks for medium traffic with different RAP aggregate percentages and sugarcane bag ash are cast. This improves the compressive strength. RAP aggregates are a suitable material that may be utilized in place of natural and artificial aggregates in construction projects. The thesis shows how discarded sugarcane ash may be used again. Several experiments were conducted to evaluate the compressive strength, density test, porosity, and permeability of the planned paver block as well as its durability.

Characterizing the Effect of Freeze-Thaw Cycling on Pore Structure of Asphalt Concrete Mixtures Using X-ray CT Scanning.

Freeze-thaw (F-T) cycling presents a challenge when building durable pavement structures in cold regions. Understanding the changes within the microstructure of asphalt concrete (AC) due to F-T conditions is crucial for developing a resilient pavement design. This study investigates the impact of F-T cycles on five AC mixtures using X-ray computed tomography (CT) scanning. Image analysis was completed to evaluate the changes in the microstructure of the AC samples before and after exposure to 30, 60, and 90 F-T cycles. The changes/degradation in the microstructure were evaluated based on analyzing the distribution and properties of air voids within the AC samples. The results showed that an X-ray CT scan can successfully capture the impact of F-T cycles on the structure of air voids in different AC mixtures. The findings of this research provide guidelines for understanding the mechanism of F-T damage within AC, which can assist in optimizing the performance of AC in cold regions.

Boosting borohydride hydrolysis for H2 generation by MOF-templated void-engineered shaggy cobalt oxide: Abundant oxygen vacancy-mediated enhancement

Designing an advantageous catalyst for enhancing the release of hydrogen (H2) from NaBH4 hydrolysis is still desirable. Herein, a void-engineered shaggy cobalt oxide (VSCO) is constructed via facile carving and calcination using the cuboid cobalt-based metal organic framework (Co-MOF) as a template. The as-prepared VSCO shows unique structural properties, such as large internal void, high specific surface area, and abundant oxygen vacancy, enabling VSCO to boost H2 production from NaBH4 hydrolysis. VSCO also exhibits an activation energy (Ea) of 28.9 kJ mol−1, which is much lower than that of commercial Co3O4 NP (62.9 kJ mol−1) and most of recent reported noble metals. VSCO also retains its outstanding catalytic activity over multiple cycles. This work sheds a light into the new approach of constructing metal oxide material with the void structure and abundant oxygen vacancies for catalyzing the hydrolysis of NaBH4.

Enhancing the Cycle Life of Solid-State Batteries by Restraining the Volume Change of Silicon Anodes

The high gravimetric and volumetric capacity of silicon makes it an attractive anode material for lithium-ion solid-state batteries (SSBs). [1,2] However, silicon suffers from high volume changes during cycling and requires high stack pressures to stabilize the interfaces. [3-5] Herein, we present different approaches to minimize the breathing of silicon-based anodes leading to stabilized cycling.Silicon carbon void structures (Si-C) obtain a void between the silicon nanoparticle and the surrounding carbon matrix to compensate the volume changes already within the anode structure. As a result, excellent cycling performance in solid-state cells with areal loadings as high as 7.4 mAh cm-2 can be demonstrated. Thereby, Si-C composite electrodes show higher lithiation capacities, better rate stability and higher capacity retentions than pristine silicon nanoparticles (SiNPs), which rapidly degrade due to the immense mechanical stress upon charging and discharging. Hence, the volume changes of the SiNPs are well compensated by the carbon matrix, which also stabilizes the entire electrode. In full cells with nickel-rich NCM (LiNi0.9Co0.05Mn0.05O2, 210 mAh g-1) as cathode, higher initial discharge capacities and coulombic efficiencies (72.7 % vs. 31.0 %) can be achieved compared to the liquid system. The solid electrolyte (Li6PS5Cl, 3 mS cm-1) does not penetrate the whole carbon matrix of the Si-C particles resulting in less side reactions. Consequently, prelithiation of the Si-C anodes is not required in SSBs. By applying either a low (1.1) or rather high n/p ratio (2.0) capacity retentions of up to 87.7 % after 50 cycles can be reached. [6]Especially for industrial fabrication of SSB anodes other procedures than the complex multi-step synthesis of e.g. Si-C composites are needed. [7] Consequently, we evaluated low-cost silicon microparticles (µm-Si) as partially lithiated electrode material (800 mAh g-1) in SSB half- and full cells. By reducing the utilized fraction of silicon, the breathing during cycling is reduced from 300 % to 66 %, which reduces the armorphization of the active material. In addition, the grain boundaries of silicon are connected by a matrix of solid electrolyte and carbon additive, which drastically reduces the need for a high stack pressure. After limiting the charge cut-off potential of NCM|SE|µm-Si full cells, significant increased capacity retentions from 32 % to 71 % after 50 cycles can be reached. In addition, similar performance compared to the Si-C electrodes can be demonstrated making it to an auspicious alternative. [8]Overall, the herein presented silicon materials achieved decent electrochemical performance without active pressure control on the cells being beneficial for electric vehicle and other applications. Hence, both Si-C and µm-Si particles are promising concepts for stable, high-capacity SSB anodes.Literature:[1] A. Mukanova, A. Jetybayeva, S.-T. Myung, S.-S. Kim, Z. Bakenov, Mater. Today Energy 2018, 9, 49.[2] N. Nitta, G. Yushin, Part. Part. Syst. Charact. 2014, 31, 317.[3] X. Su, Q. Wu, J. Li, X. Xiao, A. Lott, W. Lu, B. W. Sheldon, J. Wu, Adv. Energy Mater. 2014, 4, 1300882.[4] D. H. S. Tan, Y.-T. Chen, H. Yang, W. Bao, B. Sreenarayanan, J.-M. Doux, W. Li, B. Lu, S.-Y. Ham, B. Sayahpour et al., Science (N.Y.) 2021, 373, 1494.[5] S. Cangaz, F. Hippauf, F. S. Reuter, S. Doerfler, T. Abendroth, H. Althues, S. Kaskel, Adv. Energy Mater. 2020, 3, 2001320.[6] S. Poetke, F. Hippauf, A. Baasner, S. Dörfler, H. Althues, S. Kaskel, Batteries Supercaps 2021, 4, 1323.[7] D. Jantke, R. Bernhard, E. Hanelt, T. Buhrmester, J. Pfeiffer, S. Haufe, J. Electrochem. Soc. 2019, 166, A3881.[8] S. Poetke, S. Cangaz, F. Hippauf, S. Haufe, S. Dörfler, H. Althues, S. Kaskel, Energy Technol. 2022 submitted.

Synergistic electronic structure tuning of self-assembled hollow hierarchical Ni-Fe-Co-P nanowire arrays on carbon cloth for enhanced water splitting

The pursuit of efficient and durable catalysts utilizing non-noble metals is critical for sustainable energy conversion through electrochemical water splitting. Herein, we present a novel bifunctional electrocatalyst of Ni-Fe-Co-P nanowire arrays on carbon cloth for overall water splitting, which was synthesized via a facile ion-exchange reaction between Co-MOF nanowires array and Fe2+/Ni2+ ions, followed by NaH2PO2-assisted phosphorization. By carefully controlling the molar ratios of Ni2+/Fe2+, the solid Co-MOF nanowire were transformed into hollow hierarchical nanowires assembled by nanosheets, allowing for effective modulation of the atomic composition of the titled catalyst. Specifically, this self-supported architecture showcases various advantageous features, including substantial surface areas, elevated structural void porosity, and accessible inner surfaces. These attributes not only facilitate the exposure of abundant active sites but also bolster the structural integrity, consequently facilitating efficient mass diffusion and charge transport. Density functional theory (DFT) calculations revealed that the synergistic effect of Ni, Fe, and Co elements with phosphorus vacancies leads to an increased electron density around the Fermi level, thus optimizing the adsorption free energy of H* and improving its intrinsic catalytic activity. As expected, the optimized catalyst exhibits low overpotentials of 106 and 249 mV for achieving a current density of 10 mA cm–2 in the hydrogen and oxygen evolution reactions, in 1.0 M KOH electrolyte, respectively. Moreover, the electrocatalyst exhibits outstanding bifunctional catalytic activity, achieving a current density of 10 mA cm−2 at a low voltage of 1.62 V in a two-electrode electrolyzer system. These findings demonstrate a potential avenue for the development of efficient and cost-effective bifunctional electrocatalysts for water splitting.

Constructing bilayer-mesoporous structure in molecularly imprinted nanocomposite membranes for efficient separation of acteoside

The main active component of Cistanche tubulosa is acteoside (ACT), which is difficult to separate due to its low content. Therefore, it is important to develop an efficient method for efficient separation of ACT. Herein, the ACT-based molecularly imprinted nanocomposite membranes (A-MINMs) doped with bilayer-mesoporous carbon nanospheres (BMCNs) were fabricated for efficient separation of ACT. The designed BMCNs mixed with polyvinylidene fluoride (PVDF) powders to prepare the hybrid membranes (BMCNs@PVDF) by a phase inversion method. Then, a sol–gel method was used to synthesize the ACT-imprinted layer on the BMCNs@PVDF. The A-MINMs-400 synthesized under the given conditions demonstrated an excellent rebinding capacity of 114.94 mg/g, the brilliant permselectivity of 7.15, and the rebinding selectivity of 4.48. It mainly attributed to the following three reasons: (i) The designed BMCNs possessed a well-defined bilayer-mesoporous structure composed of the mesoporous carbon shell, interlayer void, and mesoporous carbon core. This bilayer-mesoporous structure can construct the efficient shell@void@core@void@shell pathways in A-MINMs for intercepting ACT molecules through the A-MINMs. (ii) The interlayer void structure can provide a large space for accommodating ACT molecules, thereby enhancing the rebinding capacities of A-MINMs. (iii) The introduced BMCNs nanofillers facilitated to form the abundant ACT-imprinted sites and cavities, improving the selectivity of A-MINMs for ACT. Therefore, the development and design of A-MINMs with bilayer-mesoporous nanofillers had a great potential for efficient separation of bioactive active constituents from natural products.

Highly fluorinated non-aqueous solid-liquid hybrid interface realizes water impermeability for anti-calendar aging zinc metal batteries

The thermodynamic instability of zinc metal in aqueous electrolytes is attributed to severe interfacial problems at the zinc anode. In this study, we designed and synthesized a porous-fluorinated covalent organic framework (FCOF) to encapsulate liquid perfluoropolyether (PFPE) and Zn(OTf)2 using a host-guest strategy to effectively solve the static corrosion problem of the anode. The highly fluorinate solid-liquid interface restricted free water from contacting zinc, thus greatly improving the anti-calendar aging of aqueous zinc-metal batteries. The highly fluorinated solid-liquid hybrid was constructed as a water impermeability and defect-free protection layer on the Zn surface (denoted as P-PFL@Zn). The P-PFL@Zn had integrated advantages: the liquid PFPE filled structural voids to eliminate interfacial defects, improve contact with Zn, and effectively adapt to the dynamic interface fluctuations. The solid FCOF promoted fast ion transport, provided confined space, and exhibited strong adsorption with the liquid phase, restricting the mobility of PFPE and facilitating the tight adherence of FCOF to the Zn surface. Due to the synergistic effect between the FCOF and PFPE, P-PFL@Zn exhibited a 40-day anti-calendar aging cycle, high Zn2+ transference number, ultrafast charging, and dendrite-free features. The assembled high mass-loading (20 mg cm−2) MnO2 cathode-based full cells exhibited good practical level performance under intermittent cycle mode (1000-cycle life with 90% capacity retention) and continuous cycle mode (1000-cycle life with limited Zn usage and high current density).

Improvement of microporous structure and impermeability of cement mortars using fly ash and blast furnace slag under low curing pressures

Low air pressures in high plateau will degrade the impermeability and air void structure of cement mortars. In this study, the feasibility and mechanism of fly ash (FA) and ground granulated blast furnace slag (GGBFS) improving the microporous structure and impermeability of cement mortars under low curing pressure were investigated. Results showed that the slag significantly improved the impermeability and air voids distribution of cement mortars, while the fly ash did not benefit the impermeability, as well as the air void in mixed mortars. The heat releasing rate and hydration product composition of the slag mixed paste were superior to that of the FA. The reduction of Ca(OH)2, gentler hydration rate, and filling effect of fine slag particles are believed to contribute to the improvement of impermeability. The water vapor isotherm sorption test demonstrated that low curing pressure changed the surface characteristics of hydrates, and inhibited the adsorption and desorption process (including the capillary condensation process and ink-bottle effect) with the range of relative humidity (RH) > 40%. Meanwhile, the titting parameters variation certified according to Guggenheim-Anderson-deBoer (GAB) model certified that the addition of slag achieved the same result as increasing curing pressure. Moreover, futher analysis showed that if partial OPC was replaced by slag, it could befinit energy consumption, CO2 emission, and materials cost compared with pure OPC. This study provides an initial evidence for applications of slag in low air pressure conditions.

Model aggregated 2D suspensions in shear and compression: From a fluid layer to an auxetic interface?

Hypothesis: Particle-laden interfaces play a crucial role in engineering stability of multiphase systems. However, a full understanding of the mechanical properties in shear and compression, especially in relation to the underlying microstructural changes, is as yet lacking. In this study, we investigate the interfacial rheological moduli in heterogeneous networks of aggregated 2D suspensions using different deformation modes and relate these moduli to changes in the microstructure.Experiments: Interfacial rheological experiments were conducted at different surface coverages and clean kinematic conditions, namely in (i) simple shear flow in a modified double wall-ring geometry and (ii) isotropic compression in a custom-built radial trough, while monitoring the evolution of the microstructure.Findings: The compressive moduli increase non-monotonically with decreasing void fraction, reflecting the combined effect of aggregate densification and reduction of void structures, with rotation of rigid clusters playing a significant role in closing voids. However, the shear moduli increase monotonically, which correlates with the increase in fractal dimension of the aggregates making up the backbone network. We also observe that these interfaces act as 2D auxetic materials at intermediate coverages, which is surprising given their amorphous structure. This finding has potential implications for the resilience of particle-coated bubbles or droplets subjected to time-varying compression-expansion deformations.

Detecting cosmic voids via maps of geometric-optics parameters

ABSTRACT Curved space–time geometric-optics maps derived from a deep photometric survey should contain information about the 3D matter distribution and thus about cosmic voids in the survey, despite projection effects. We explore to what degree sky-plane geometric-optics maps can reveal the presence of intrinsic 3D voids. We carry out a cosmological N-body simulation and place it further than a gigaparsec from the observer, at redshift 0.5. We infer 3D void structures using the watershed algorithm. Independently, we calculate a surface overdensity map and maps of weak gravitational lensing and geometric-optics scalars. We propose and implement a heuristic algorithm for detecting (projected) radial void profiles from these maps. We find in our simulation that given the sky-plane centres of the 3D watershed-detected voids, there is significant evidence of finding corresponding void centres in the surface overdensity Σ, the averaged weak-lensing tangential shear $\overline{{\gamma }_{\perp }}$, the Sachs expansion θ, and the Sachs shear modulus |σ|. Recovering the centres of the 3D voids from the sky-plane information alone is significant given the Sachs expansion θ, or the Sachs shear |σ|, mildly significant given the weak-lensing shear $\overline{{\gamma }_{\perp }}$, and not significant for the surface overdensity Σ. Void radii are uncorrelated between 3D and 2D voids; our algorithm is not designed to distinguish voids that are nearly concentric in projection. This investigation shows preliminary evidence encouraging observational studies of gravitational lensing through individual voids, either blind or with spectroscopic/photometric redshifts. The former case – blind searches – should generate falsifiable predictions of intrinsic 3D void centres.

Electrolyte Permeability in Plastic Ice VII.

Deep brines in water-rich planets form when electrolytes diffuse from the rocky interior through layers of thick dense ice such as ice VII and the hypothesized plastic ice VII. We perform classical molecular dynamics simulations of Li+, Na+, and K+ alkali ions and F- and Cl- halide ions in plastic ice VII at conditions similar to water-rich super-Earths, icy moons, and ocean worlds. We find that plastic ice VII is permeable to electrolytes on geological timescales. Diffusion occurs via jumps between adjacent voids in the bcc crystal structure and is governed by molecular rotations. An exception to this mechanism is Na+ which, at variance with other ions, can substitute water molecules on lattice positions. The bulk modulus of pristine plastic ice VII is dependent on the pace of molecular rotations: when the rotations are slow, the bulk modulus is 1 order of magnitude lower compared to the bulk modulus at conditions of fast rotations, hence providing direct evidence of the role of molecular rotations in determining elastic properties. Electrolytes affect the bulk modulus only at high-concentration conditions and slow molecular rotations. Our results show that plastic ice VII may facilitate the development of brines in water-rich planets and ocean worlds, with a clear significance for their potential to support exobiology and for the chemical evolution of their aqueous reservoirs.

A Semi-Three-Dimensional Bioprinted Neurocardiac System for Tissue Engineering of a Cardiac Autonomic Nervous System Model.

In this study, we designed a tissue-engineered neurocardiac model to help us examine the role of neuronal regulation and confirm the importance of neural innervation techniques for the regeneration of cardiac tissue. A three-dimensional (3D) bioprinted neurocardiac scaffold composed of a mixture of gelatin-alginate and alginate-genipin-fibrin hydrogels was developed with a 2:1 ratio of AC16 cardiomyocytes (CMs) and retinoic acid-differentiated SH-SY5Y neuronal cells (NCs) respectively. A unique semi-3D bioprinting approach was adopted, where the CMs were mixed in the cardiac bioink and printed using an anisotropic accordion design to mimic the physiological tissue architecture in vivo. The voids in this 3D structure were methodically filled in using a NC-gel mixture and crosslinked. Confocal fluorescent imaging using microtubule-associated protein 2 (MAP-2) and anticholine acetyltransferase (CHAT) antibodies for labeling the NCs and the MyoD1 antibody for the CMs revealed functional coupling between the two cell types in the final crosslinked structure. These data confirmed the development of a relevant neurocardiac model that could be used to study neurocardiac modulation under physiological and pathological conditions.

Investigation of mechanical performance and voids structure of cement-stabilised macadam under freeze-thaw actions

ABSTRACT In cold regions, the mechanical performance of cement-stabilised macadam (CSM) deteriorates significantly due to freeze–thaw (F-T) actions. This paper attempts to investigate the F-T attenuation mechanism of mechanical performance of CSM from the perspective of the evolution of voids structure. To this end, multiple groups performance tests were conducted to study the effect of cement content, freezing temperature, and humidity conditions on the mechanical performance of CSM. Then the size distribution and evolution process of internal voids of CSM after F-T actions were investigated by computed tomography (CT) test. The results indicate that the resilient modulus (RM) and compressive strength (CS) of CSM decrease when F-T cycles increase until 15, and then stabilise gradually with a reduction of less than 5% in the last 5 cycles. It is presumbly attributed to the generation and melt of ice lenses in voids, distorting original matrix of particles. Additionally, increasing cement content can reduce the deterioration of mechanical performance, while increasing moisture content and decreasing freezing temperature promote the deterioration of mechanical performance. The F-T actions cause volume expansion of the larger voids (>100 mm3) before 5 cycles and then mainly result in more small voids (<1 mm3) during 5∼15 cycles. There is an apparent linear relationship between average voids ratio and RM and CS for CSM. The correlation coefficient R 2 is higher than 0.92 and 0.73, respectively.

Using elliptical galaxy kinematics to compare the strength of gravity in cosmological regions of differing gravitational potential – a first look

ABSTRACT Various models of modified gravity invoke ‘screening’ mechanisms that are sensitive to the value of the local gravitational potential. This could have observable consequences for galaxies. These consequences might be seen by comparing two proxies for galaxy mass – their luminosity and their internal kinematics – as a function of local galaxy density. Motivated by this prospect, we have compared the observed properties of luminous red galaxies (LRGs) inside and outside of voids in the cosmic large scale structure. We used archival measurements of line widths, luminosities, redshifts, colours, and positions of galaxies in conjunction with recent void catalogues to construct comparison LRG samples inside and outside of voids. We fitted these two samples to the well-established fundamental plane of elliptical galaxies to constrain any differences between the inferred value of the Newtonian gravitational constant G for the two samples. We obtained a null result, with an upper limit on any fractional difference in G within and outside of cosmological voids to be α = δG/G ∼ 40 per cent. This upper bound is dominated by the small-number statistics of our N ∼ 100 within-void LRG sample. With the caveat that environmental effects could influence various parameters such as star formation, we estimate that a 1 per cent statistical limit on α could be attained with data from 105 elliptical galaxies within voids. This is within the reach of future photometric and spectroscopic surveys, both of which are required to pursue this method.

Iron doping and interface engineering on amorphous/crystalline Fe-NixSy heterostructures toward high-stability and kinetically accelerated water splitting

It is very important to develop transition metal-based electrocatalysts with excellent activity, high stability and low-cost for overall water splitting. In this work, the Fe-doped NixSy/NF amorphous/crystalline heterostructure nanoarrays (Fe-NixSy/NF) was synthesized by a simple one-step method. The resulting hierarchically structured nanoarrays offer the advantages of large surface area, high structural void fraction and accessible internal surfaces. These advantages not only furnish additional catalytically active sites, but also enhance the stability of the structure and effectively accelerate mass diffusion and charge transport. Experimental and characterization results indicate that Fe doping increases the electrical conductivity of amorphous/crystalline NixSy/NF, and the NiS-Ni3S2 heterojunctions evoke interfacial charge rearrangement and optimize the adsorption free energy of the intermediates, which allows the catalyst to exhibit low overpotential and superior electrocatalytic activity. Especially, the overpotentials of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) of Fe-NixSy/NF at 10 mA cm−2 in an alkaline environment are 102.4 and 230.5 mV, respectively. When applied as a bifunctional catalyst for overall water splitting, it requires only 1.45 V cell voltage to deliver a current density of 10 mA cm−2, which is preferable to the all-noble metal Pt/C || IrO2 electrocatalyst (1.62 mV @ 10 mA cm−2). In addition, Fe-NixSy/NF has excellent stability, and there is no obvious degradation after 96 h continuous operation at a current density of 100 mA cm−2. This work affords insights into the application of doping strategies and crystalline/amorphous synergistic modulation of the electrocatalytic activity of transition metal-based catalysts in energy conversion systems.

3D printed porous particle and its geotechnical properties

The study of effects of particle breakage on the mechanical properties of soil composed of porous particles is challenging due to the heterogeneity of the shape and inner void structure of individual particles, even for an identical soil sample, which imparts a compound effect on the mechanical properties. Advancements in three-dimensional (3D) printing technique have enabled the replication of objects with the same shape but different inner structures. This study investigated the feasibility of replicating porous and non-porous particles with the same particle shape characteristics, such as form, waviness, and texture, using 3D printing technique. The particle shape characteristics were evaluated using image analysis. Single particle crushing and triaxial compression tests were conducted to characterize the mechanical properties of the 3D printed and porous volcanic soil particles. It is observed that the mechanical response in the single particle crushing test varies for volcanic soil, which may be attributed to the heterogeneity in the shape and porosity of the particles. However, for each type of 3D printed particle, the response has a high repeatability and varies based on particle porosity. Furthermore, the effects of porosity on the shear response are demonstrated through triaxial tests on 3D printed particles of different porosities. It is noted that although a quantitative comparison is not possible, a qualitative similarity is observed in the response of the 3D printed porous particles with natural porous volcanic soil. Thus, insights into the mechanical response of porous particles can be gained using 3D printed particles.

Characteristics of Internal Water Flow Conduction within Asphalt Mixtures Based on Real Three-Dimensional Void Structure

This work presents a new approach to investigating water conduction properties in real three-dimensional (3D) voids of asphalt mixtures. Three different molding methods were employed for the same grade of asphalt mixture, and the three asphalt mixture specimens were scanned using X-ray Computerized Tomography (CT) to identify the real 3D void structure distribution inside the mixture. The real 3D behavior of void moisture conduction inside the mixture was simulated using the discrete lattice Boltzmann method and the BGK collision model. Three different molding methods were used to study the behavior of mesoscopic seepage inside the specimen. The results show that water conduction varies substantially in real 3D voids inside diverse molded objects. Regardless of flow and flow velocity, the Superpave Gyratory Compactor (SGC) method is extraordinarily close to the conduction qualities of the actual field core material. It shows that the Marshall molding method is inconsistent with the actual pavement molding method, and the SGC method can not only ensure that the reasonable void ratio is conducive to the thermal expansion and cold shrinkage space of the asphalt mixture but also prevents rainwater from entering the asphalt mixture. This work provides a new perspective for the study of water damage resistance and medium transmission characteristics of asphalt mixtures.

Optical sensor array of metal-organic-framework-based inverse opal films for the detection and identification of various alcohols

Reliable and inexpensive sensors for the detection and discrimination of various volatile organic compounds like different alcohols are required for many applications, for example to proof the alcohol quality and for avoiding methanol poising. Here, we develop a sensor array of films made of different types of surface-mounted metal-organic frameworks (SURMOFs) with a periodic three-dimensional structure of mesoscopic voids, referred to as inverse opal structure. The wavelength shift (or alternatively, the intensity change) of the photonic reflectance peak caused by the analyte vapor adsorption in the SURMOF was used as signal. The sensor array is applied for the detection of various pure low-carbon alcohols, which are methanol, ethanol, 1-propanol, and 1-butanol. The sensor array shows a low limit of detection (LOD) in the range of 10–60 ppm and is able to reliably discriminate the alcohols from each other. Furthermore, the sensor array is able to precisely discriminate their pure vapors and binary mixtures with methanol. We foresee such sensor array with SURMOF-based inverse opal films offer a great potential for the precise and cost-efficient detection of various analytes.