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Bentonite pellets are recognized as good buffer/backfill materials for sealing technological voids in high-level radioactive waste (HLW) repository. Compared to that of a traditional compacted bentonite block, one of the most important particularities of this material is the initially discrete pellets and the inevitable heterogeneous porosity formed, leading to a distinctive water retention behaviour. In this paper, water retention and mercury intrusion porosimetry (MIP) tests were conducted on pellet mixture (constant volume), single pellet (free swelling) and compacted block (constant volume) of GMZ bentonite, water retention properties and pore structure evolutions of the specimens were comparatively investigated. Results show that the water retention properties of the three specimens are almost similar to each other in the high suction range (> 10 MPa), while the water retention capacity of pellet mixture is lower than those of the compacted block and single pellet in the low suction range (< 10 MPa). Based on the capillary water retention theory (the Young–Laplace equation), a new concept ‘saturated void ratio’ that was positively related to water content and dependent on pore size distribution of the specimen was defined. Then, according to the product of saturated void ratio and water density in saturated void, differences of water retention properties for the three specimens at low suctions were explained. Meanwhile, MIP tests indicate that as suction decreases, the micro- and macrovoid ratios of pellet mixture and compacted block decrease as the mesovoid ratio increases, while all the void ratios of single pellets increase. This could be explained that upon wetting, water is successively adsorbed into the inter-layer, inter-particle and inter-pellet voids, leading to the subdivision of particles and swelling of aggregates and pellets. Under constant volume condition, aggregates and pellets tend to swell and fill into the inter-aggregates or inter-pellets voids. While under free swelling condition, the particles and aggregates in a single pellet tend to swell outward rather than squeezing into the inter-aggregate voids, leading to the expansion of the pores and even formation of cracks. Results including the effects of initial conditions (initial dry density and fabric) and constraint conditions (constant volume or free swelling) on the water retention capacity and pore structure evolution reached in this work are of great importance in designing of engineering barrier systems for the HLW repository.

There is, in general, a dearth of empirical inquiries on how institutional voids are filled through institutional work in marginalized communities. Extant studies have focussed on institutional work that addresses solitary institutional void, mostly in formal settings. In this paper, we inquire the case of a social entrepreneurial venture in India that identified two complementary institutional voids (productive ageing void of the urban elderly and rural education void of children) and attempted to simultaneously address the two voids. The issue of physical distance between the two groups was overcome by enacting an ICT platform. We also show how the institutional challenges associated with the ICT implementation led them to pursue different kinds of institutional works in their context. We then identify different theoretical dimensions of institutional works that could be used in marginalized contexts. Finally, we show how the ‘complementary voids’ approach has implications for both theory and practice.

The air voids is a critical indicator in the design of porous asphalt mixture (PA). Currently, aggregate gradation design for PA uses air voids solely as a verification indicator, rather than integrating it directly into the gradation design process, which may lead to PA design tedious and time-consuming. The objective of this study was to present a method for designing the aggregate gradation of PA based on the target air voids. Initially, using the volume composition of compacted asphalt mixtures and the formula for estimating asphalt-aggregate ratio, a physical model was established to link air voids with the content of fine materials (i.e. passing percentage of key sieves). Subsequently, a determination method for the critical parameter of the percentage voids in coarse aggregate (VCA) within the physical model was provided based on the skeleton stability of coarse aggregate using a penetration test. Finally, a procedure for designing the aggregate gradation of PA based on target air voids was proposed employing the established physical model. Additionally, an applied case study on the gradation design of PA-13 was presented, verifying the effectiveness of the method. The design method proposed in the paper can serve as a reference for aggregate gradation design of PAs with various requirements for air voids, significantly reducing the experimental workloads and time.

The performance of an asphalt mixture will deteriorate under the condition of salt erosion, but there are different opinions on the mechanism of deterioration. Few studies have focused on the relation between the change of void characteristics and performance deterioration of an asphalt mixture exposed to salt erosion. To explore the relation between the air voids characteristics of an asphalt mixture and mechanical damage under salt erosion, the mechanical damage in an asphalt mixture was measured by splitting strength. The asphalt mixture specimens, immersion solutions, asphalt mortar, and aggregate were scanned with CT technology. To segment the voids, the Otsu method was used over asphalt mortar and solution range of CT values. A three-dimensional reconstruction of the CT image was performed with Mimics 20 software to calculate the asphalt mixture’s void characteristics. On this basis, the relationships between the change in void characteristics and splitting strength were analyzed. The results showed that the ideal calculated void fraction can be obtained by threshold segmentation of the image void/asphalt mortar interface with the local CT value Otsu method. Under the salt corrosion environment, the increase of open voids of an asphalt mixture is linearly correlated with the decrease of splitting strength, while salts’ crystallization in the open voids produces crystallization pressure, accelerating the volume growth of open voids. The early damage of an asphalt mixture suffered from the salt may be mainly physical damage. These results can provide a useful reference for the performance of damage research on asphalt mixtures in salt enrichment areas.

The digital elevation model (DEM) acquired through photogrammetry or LiDAR usually exposes voids due to phenomena such as instrumentation artifact, ground occlusion, etc. For this reason, this paper proposes a multiattention generative adversarial network model to fill the voids. In this model, a multiscale feature fusion generation network is proposed to initially fill the voids, and then a multiattention filling network is proposed to recover the detailed features of the terrain surrounding the void area, and the channel-spatial cropping attention mechanism module is proposed as an enhancement of the network. Spectral normalization is added to each convolution layer in the discriminator network. Finally, the training of the model by a combined loss function, including reconstruction loss and adversarial loss, is optimized. Three groups of experiments with four different types of terrains, hillsides, valleys, ridges and hills, are conducted for validation of the proposed model. The experimental results show that (1) the structural similarity surrounding terrestrial voids in the three types of terrains (i.e., hillside, valley, and ridge) can reach 80–90%, which implies that the DEM accuracy can be improved by at least 10% relative to the traditional interpolation methods (i.e., Kriging, IDW, and Spline), and can reach 57.4%, while other deep learning models (i.e., CE, GL and CR) only reach 43.2%, 17.1% and 11.4% in the hilly areas, respectively. Therefore, it can be concluded that the structural similarity surrounding the terrestrial voids filled using the model proposed in this paper can reach 60–90% upon the types of terrain, such as hillside, valley, ridge, and hill.

Voids in electroless copper (Cu) plating layers critically influence the reliability of microvias in high-density interconnect (HDI) packaging substrates. This study investigates void formation mechanisms by fabricating multilayered Cu structures that simulate microvia interconnections and performing electroless Cu plating under controlled nickel (Ni) ion concentrations and bath temperatures. Void morphology and distribution are analyzed using transmission electron microscopy (TEM) and quantitative image analysis. The results reveal that increased Ni content and elevated bath temperatures accelerate the plating rate, thereby promoting void formation at the initial stage of deposition. Theoretical analysis suggests that this behavior is driven by surface cohesion forces acting on nascent voids. A void growth mechanism is proposed, wherein voids predominantly originate within the initial Cu layer due to localized hydrogen accumulation near palladium (Pd) catalysts. In contrast, subsequent layers—deposited after Pd sites are buried—exhibit reduced maximum (max.) void sizes and lower void fractions. These findings provide mechanistic insight into void evolution in electroless Cu layers and underscore the critical role of Ni content and bath temperature in enhancing HDI packaging substrate reliability.

High-capacity alloy anode materials for Li-ion batteries have long been held back by limited cyclability caused by the large volume changes during lithium insertion and removal. Hollow and yolk-shell nanostructures have been used to increase the cycling stability by providing an inner void space to accommodate volume changes and a mechanically and dimensionally stable outer surface. These materials, however, require complex synthesis procedures. Here, using in situ transmission electron microscopy, we show that sufficiently small antimony nanocrystals spontaneously form uniform voids on the removal of lithium, which are then reversibly filled and vacated during cycling. This behaviour is found to arise from a resilient native oxide layer that allows for an initial expansion during lithiation but mechanically prevents shrinkage as antimony forms voids during delithiation. We developed a chemomechanical model that explains these observations, and we demonstrate that this behaviour is size dependent. Thus, antimony naturally evolves to form optimal nanostructures for alloy anodes, as we show through electrochemical experiments in a half-cell configuration in which 15-nm antimony nanocrystals have a consistently higher Coulombic efficiency than larger nanoparticles.Sufficiently small antimony nanoparticles form uniform voids that are reversibly filled and vacated during cycling.

In order to effectively utilize the magnetic-dielectric synergy and interfacial engineering, in this paper, yolk—shell structured magnetic multicomponent nanocomposites (MCNCs) including CoNi@void@C and CoNi@void@C@MoS 2 were produced in large scale by in-situ pyrolysis of cubic CoNi Prussian blue analogs (PBAs) followed by the hydrothermal process, respectively. Because of their unique structures, excellent synergistic effect between dielectric and magnetic loss, the as-prepared CoNi@void@C and CoNi@void@C@MoS 2 MCNCs displayed very outstanding electromagnetic wave absorption performances (EMWAPs) including strong absorption capabilities, broad absorption bandwidth and thin matching thicknesses. Furthermore, the as-prepared CoNi@void@C and CoNi@void@C@MoS 2 MCNCs well maintained the cubic configuration of CoNi PBAs even after the thermal treatment and hydrothermal processes. The unique structure and formed carbon layers effectively prevented the corrosion of internal CoNi alloy during the formation of MoS 2 , and CoNi@void@C@MoS 2 MCNCs with different MoS 2 contents could be synthesized by controlling the hydrothermal temperature. The obtained results revealed that the EM parameters, dielectric and magnetic loss capabilities of CoNi@void@C@MoS 2 MCNCs could be tuned by controlling hydrothermal temperature and filler loading, which made their outstanding EMWAPs could be achieved in different frequency regions. Taking account of simple process, low density and high chemical stability, our findings provided a new and effective pathway to develop the strong wideband microwave absorbers.

Oxygen redox cathodes, such as Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 , deliver higher energy densities than those based on transition metal redox alone. However, they commonly exhibit voltage fade, a gradually diminishing discharge voltage on extended cycling. Recent research has shown that, on the first charge, oxidation of O 2− ions forms O 2 molecules trapped in nano-sized voids within the structure, which can be fully reduced to O 2− on the subsequent discharge. Here we show that the loss of O-redox capacity on cycling and therefore voltage fade arises from a combination of a reduction in the reversibility of the O 2− /O 2 redox process and O 2 loss. The closed voids that trap O 2 grow on cycling, rendering more of the trapped O 2 electrochemically inactive. The size and density of voids leads to cracking of the particles and open voids at the surfaces, releasing O 2 . Our findings implicate the thermodynamic driving force to form O 2 as the root cause of transition metal migration, void formation and consequently voltage fade in Li-rich cathodes. Oxygen redox cathodes deliver higher energy densities than those based on transition metal redox but commonly exhibit voltage fade on extended cycling. The loss of O-redox capacity and voltage fade is shown to arise from a reduction in O 2− /O 2 redox process reversibility and O 2 loss.

One-dimensional compression tests on quartz sands treated by microbially induced carbonate precipitation (MICP) were carried out to evaluate the effects of gradation and calcium carbonate (CaCO3) content on compression behaviors. The experimental results reveal that the compressibility of specimens increases with increasing coefficient of uniformity or decreasing CaCO3 content. The evolution of void ratio with vertical stress could be generally characterized into three stages based on the underlying mechanisms. The initiation of bond breakage occurs around vertical stress of 0.036 MPa, and the dominating mechanism transits to particle breakage around vertical stress of 8.3 MPa. Scanning electron microscope analyses demonstrate that bonding effect and coating effect of CaCO3 precipitation are responsible for the lower compressibility of MICP-treated specimen. The presence of small particles leads to more interparticle CaCO3 bonds whose breakage would still allow the small particles to fill the intercoarse-grain voids.