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Adsorptive C2H2/C2H4 separation using metal–organic frameworks (MOFs) has emerged as a promising technology for the removal of C2H2 (acetylene) impurity (1 %) from C2H4 (ethylene). The practical application of these materials involves the optimization of separation performance as well as development of scalable and green production protocols. Herein, we report the efficient C2H2/C2H4 separation in a MOF, Cu(OH)INA (INA: isonicotinate) which achieves a record C2H2 packing density of 351 mg cm−3 at 0.01 bar through high affinity towards C2H2. DFT (density functional theory) calculations reveal the synergistic binding mechanism through pore confinement and the oxygen sites in pore wall. The weakly basic nature of binding sites leads to a relatively low heat of adsorption (Qst) of approximately 36 kJ/mol, which is beneficial for material regeneration and thermal management. Furthermore, a scalable and environmentally friendly synthesis protocol with a high space‐time yield of 544 kg m−3 day−1 has been developed without using any modulating agents. This material also demonstrates enduring separation performance for multiple cycles, maintaining its efficacy after exposure to water or air for three months. [ABSTRACT FROM AUTHOR]

This study investigates methods to enhance the permeability of metal magnetic composites, crucial for the performance of thin film power inductors in high-frequency applications, such as those in contemporary smartphones operating in the MHz range. Traditional reliance on ferrite magnetic materials is eschewed in favor of metal magnetic materials combined with epoxy to create novel composites aimed at optimizing packing density and significantly increasing magnetic permeability. The impact on permeability is explored using four different metal powders: pure iron (FE), Fe-Si (FS), Fe-Si-B-C-Cr (AM), and Fe-Si-B-Nb-Cu (NC). The FE sample is produced using carbonyl iron powder, resulting in a particle size (D50) of 2.1 μm. The FS sample, produced through gas atomization, has a particle size of 17.5 μm, while the AM and NC samples, produced via water atomization, yield particle sizes (D50) of 19.4 μm and 23 μm, respectively. Analyses using X-ray diffraction (XRD) and Mösbauer spectroscopy reveal that FE and FS samples have crystalline structures, whereas AM and NC are amorphous. Scanning electron microscopy confirms the spherical shape of particles in all samples. Theoretical calculations, based on Ollendorff's theory of permeability and Suzuki and Oshima's models on packing fraction, suggest that a composite with a ratio of 8:1.2:0.8 and particle sizes of approximately 25 μm, 1.5 μm, and 0.1 μm, respectively, could achieve a permeability value of up to 138.1. This demonstrates the potential for achieving high permeability at MHz frequencies through strategic packing of voids with submicron and nanopowders, marking a significant advancement in the field of thin film power inductors. [ABSTRACT FROM AUTHOR]

Abstract\nHIGHLIGHTSThe aggregate size and particle-size distribution (PSD) can change the packing density, slump, and strength of concrete. The micromechanical effects of aggregate size on the slump and strength remain unclear. The current numerical study examined concrete behavior using slump and uniaxial compressive strength (UCS) tests considering the aggregate size distribution using the discrete element method. The effect of the aggregate size on the packing density, UCS, and slump of the concrete was analyzed. To accomplish this, we evaluated how variations in the uniformity and curvature coefficients of the PSD, as well as the specific surface area of the samples, were affected by changes in aggregate size. Although the simulations were based on standard specimens from the laboratory, the results showed good agreement with the documented experimental results. Briefly, at a 40–60% fine aggregate content, the packing density and compressive strength of the concrete reached their peaks and caused a decrease in the height of the slump. The uniformity and curvature coefficients did not influence the slump height. The induced shear band could be tracked during the UCS tests and the crack angles could be measured. At the optimum fine content (40–60%), the shear bands were primarily localized and propagated through the samples having different fine contents.The use of the optimum level of the concrete fine aggregate content ensured its workability and strength.This optimum level of fine aggregate was 40–60%.The discrete element method can be used to evaluate the role of particle size on the performance of concrete.The particle size distribution changed the macro-parameters of the concrete.The maximum packing density was determined to be 40–60% of fine aggregates.The use of the optimum level of the concrete fine aggregate content ensured its workability and strength.This optimum level of fine aggregate was 40–60%.The discrete element method can be used to evaluate the role of particle size on the performance of concrete.The particle size distribution changed the macro-parameters of the concrete.The maximum packing density was determined to be 40–60% of fine aggregates. [ABSTRACT FROM AUTHOR]

To investigate the mechanism of polypropylene fiber (PPF) on the rheological and thixotropic properties of cemented paste backfill containing mineral admixtures, the concept of water film thickness (WFT) was introduced. The packing density of the tailings-binder-PPF (TBP) system was measured in dry and wet conditions and the WFT was calculated accordingly. Additionally, the rheological parameters (yield stress, thixotropy, etc.) of the fiber-reinforced cemented paste backfill (FRCPB) were quantified. The results demonstrate that the wet packing test is a more appropriate method for measuring the packing density of the TBP system. The PPF length has a slight adverse effect on the packing density, and the packing density initially increases and then decreases with the PPF content. The reasons can be attributed to the filling effect and wedge effect of the fibers, respectively. In addition to the packing density, the thixotropy of FRCPB is also affected by the interaction of fibers. WFT is a crucial factor affecting the yield stress of FRCPB, with which it exhibits a strong linear relationship. The study identified that the optimum PPF content for enhancing the rheological and thixotropic properties of CPB is 0.2%, with a fiber length of 9 mm, balancing flowability and stability for practical application in mining backfill operations. These insights can guide the optimization of CPB mixtures, enhancing their flowability and stability during placement in mined-out spaces. By improving the fill quality and reducing the risk of blockage during backfill operations, the results offer practical benefits in increasing the safety and efficiency of underground mining activities. [ABSTRACT FROM AUTHOR]

To investigate the effects of the combined addition of Lactiplantibacillus plantarum and sucrose on the fermentation weight loss (FWL), fermentation quality, and microbial community structure of ensiled rape straw under varying packing density conditions. After harvesting, the rapeseed straw was collected, cut into 1–2 cm pieces, and sprayed with sterile water to adjust the moisture content to 60%. The straw was then divided into two groups: one treated with additives (1 × 105 CFU/g fresh material of Lactiplantibacillus plantarum and 10 kg/t fresh material of sucrose), and the other sprayed with an equivalent amount of sterile water as the control (CK). The treated materials were thoroughly mixed and packed into silos at densities of 450, 500, and 550 kg/m3. FWL was recorded on days 1, 3, 6, 15, 20, and 45 of fermentation. On day 45, the samples were analyzed for fermentation quality, microbial counts, and microbial diversity. FWL increased significantly (p < 0.05) in both the treated (LS) and control groups during fermentation. The LS group showed higher lactic acid (LA) levels (p < 0.05) and lower ammonia nitrogen levels (p < 0.05) compared to CK. The CK group had significantly higher (p < 0.05) counts of Coliforms and lower bacterial counts (p < 0.05) than LS. The dominant genera in the silage were Xanthomonas, Lactiplantibacillus plantarum, and Lentilactobacillus. In the LS group, the relative abundances of Lactiplantibacillus plantarum and Lentilactobacillus ranged from 16.93% to 20.43% and 15.63% to 27.46%, respectively, with their combined abundance being higher than in CK. At a packing density of 500 kg/m3, the relative abundances of Lactiplantibacillus plantarum and Lentilactobacillus in the LS group were significantly higher (p < 0.05) than in CK. Increasing packing density and applying additives to rape straw silage effectively reduced FWL, improved fermentation quality, boosted the relative abundance of beneficial lactic acid bacteria, and decreased the presence of undesirable bacteria such as Enterobacter and Bacillus. [ABSTRACT FROM AUTHOR]

Lightweight aggregate concrete (LWAC) is gaining interest due to its reduced weight, high strength, and durability while being cost-effective. This research proposes a method to design an LWAC by integrating coconut shell (CS) as coarse lightweight aggregate and a high volume of wet-grinded ultrafine ground granulated blast furnace slag (UGGBS). To optimize the mix design of LWAC, a particle packing model was employed. A comparative analysis was conducted between normal-weight concrete (M40) and the optimized LWAC reinforced with basalt fibers (BF). The parameters analyzed include CO2 emissions, density, surface crack conditions, water absorption and porosity, sorptivity, and compressive and flexural strength. The optimal design was determined using the packing density method. Also, the impact of BF was investigated at varying levels (0%, 0.15%, and 1%). The results revealed that the incorporation of UGGBS had a substantial enhancement to the mechanical properties of LWAC when BF and CS were incorporated. As a significant finding of this research, a grade 30 LWAC with demolded density of 1864 kg/m3 containing only 284 kg/m3 cement was developed. The LWAC with high-volume UGGBS and BF had the minimum CO2 emissions at 390.9 kg/t, marking a reduction of about 31.6% compared to conventional M40-grade concrete. This research presents an introductory approach to sustainable, environmentally friendly, high-strength, and low-density concrete production by using packing density optimization, thereby contributing to both environmental conservation and structural outcomes. [ABSTRACT FROM AUTHOR]

In this study, nature, physical characteristics and γ-ray protection features of the 50B2O3 + 1Tb4O7 + (20-X)SiO2 + 19BaF2 + 10Li2O + XAg2O, where X = 0–5 mol% glasses were investigated. Samples were prepared using the melt quenching procedure and named AgOX. The MCNP simulation code and EpiXs software (EPX) were applied to achieve the mentioned aims. XRD measurements confirmed the amorphous nature of AgOX samples. The density (Ds) of AgOX enhanced from 2.61 g/cm3 to 2.92 g/ cm3 as AgO content increased from 0.0 to 5.0 mol%. Molar volume (Vm) declined from 35.06 cm3/mol to 34.02 cm3/mol. The packing density (Pd) enhanced from 0.517 to 0.533, while the free volume (Vf) changed from 16.37 cm3/mol for the AgO0 sample to 15.86 cm3/mol for the AgO5 sample. Linear-attenuation (µ) order was AgO0 < AgO1 < AgO2 < AgO3 < AgO5. The AgO5 sample possessed the lowest half (HVL) and tenth (TVL)-value layers as well as mean free path (MFP). Within the investigated energy range of effective atomic number ( Z ef) within the range: 44.540 – 15.220, 44.599 – 15.580, 44.653 – 15.929, 44.704 – 16.269, and 44.797 – 16.922 for AgO0, AgO1, AgO2, AgO3, and AgO5 glasses, respectively. The AgO5 sample offers the best γ-ray shielding capability among AgOX glasses. [ABSTRACT FROM AUTHOR]

Self-compacting concrete (SCC), known for its excellent fluidity and self-compacting ability, is widely used in civil engineering. To enhance the comprehensive performance of SCC, dolomite powder (DP) is integrated as a substitute for cement. This study aims to analyze the impact of DP on the yield stress relationship between self-compacting mortar (SCM) and self-compacting paste (SCP) from a multi-scale perspective. A new predictive model for the yield stress relationship between SCM and SCP incorporating DP is established by improving the n value in the existing ϕ e model, which characterizes the sensitivity of the mortar yield stress relative to changes in the paste yield stress. By conducting mini-slump flow tests on nine sets of cement–DP mixtures, it is found that DP impacts the yield stress relationship between SCM and SCP mainly through changes in the inter-particle filling effect, and the n value in the predictive model is roughly between 2.4 and 3.6. When the DP content is kept constant and the particle size is changed, the n value shows a strong positive linear relationship with the packing density of the paste ( ϕ e , p ). The relationship between n and ϕ e , p is derived using the linear fitting method, which improves the model's predictive accuracy by 95.2%. [ABSTRACT FROM AUTHOR]

Powder deposition of even and homogeneous layers is a major aspect of every powder bed fusion process. Powder sieving is commonly performed to powder batches outside of the PBF machine, prior to the part manufacturing stage. In this work, sieving is examined as a method of powder deposition rather than a method to solely filter out agglomerates and oversized particles. Initially, a DEM powder model that has been validated experimentally is implemented, and the sieving process is modelled. The sieving process is optimized in order to maximize mass flow, duration of its linear stage and total mass sieved during linearity. For this, a Taguchi design of experiments with subsequent analysis of variance is deployed, proving that the larger the initial powder loaded in the sieve, the larger the sieve stimulation necessary, both in terms of oscillating frequency and amplitude. The sieve's aperture shape is also evaluated, proving that the more sides the canonical polygon has, the less the mass flow per aperture for the same maximum passing particle size. Then, the quality of the layer produced via controlled sieving is examined via certain layer quality criteria, such as the surface roughness, layer thickness deviation, surface coverage ratio and packing density. The findings prove that controlled sieving can outperform powder deposition via a non-vibrated doctor blade recoater, both in terms of layer surface quality and duration of layer deposition, as proven by surface skewness and kurtosis evaluation. [ABSTRACT FROM AUTHOR]

Powder deposition is a very important aspect of PBF-based additive manufacturing processes. Discrete Element Method (DEM) is commonly utilized by researchers to examine the physically complex aspects of powder-spreading methods. This work focuses on vibration-assisted doctor blade powder recoating. The aim of this work is to use experiment-verified DEM simulations in combination with Taguchi Design of Experiments (DoE) to identify optimum spreading parameters based on robust layer quality criteria. The verification of the used powder model is performed via angle of repose and angle of avalanche simulation–experiment cross-checking. Then, four criteria, namely layer thickness deviation, surface coverage ratio, surface root-mean-square roughness and true packing density, are defined. It has been proven that the doctor blade's translational speed plays the most important role in defining the quality of the deposited layer. The true packing density was found to be unaffected by the spreading parameters. The vertical vibration of the doctor blade recoater was found to have a beneficial effect on the quality of the deposited layer. Ultimately, a weighted mean quality criteria analysis is mapped out. Skewness and kurtosis were proven to function as effective indicators of layer quality, showing a linear relation to the weighted means of the defined quality criteria. The specific weights that optimize this linearity were identified. [ABSTRACT FROM AUTHOR]

Sustainability and limitations in embedded reinforcement are the main obstacles in digital fabrication with concrete. This study proposed a 3D printable fiber-reinforced calcined clay-limestone-based cementitious material (FR-LC3). The binder systems incorporating calcined clay (CC) and limestone filler (LF) were optimized by determining the flow characteristics and water retention ability of the paste. The effect of fiber volume on the key fresh and mechanical properties of the fiber-reinforced mortars made with the optimized binder was evaluated. A combination of offline assessments and inline printing were employed to investigate the printability of the FR-LC3 with various binder systems and viscosity-modifying admixture (VMA) dosages. The results revealed that the binary system with 20% CC and the ternary system containing 30% CC and 15% LF were highly advantageous, with enhanced packing density, robustness, and water retention ability. Incorporating 2% 6-mm steel fiber contributed to the highest 28-day compressive and flexural strengths and toughness without significantly compromising the fluidity. Finally, the developed FR-LC3 mixtures were successfully printed using an extrusion-based 3D printer. The LF addition in the ternary system decreased the maximum buildable height of a single-wall printed object while reducing the SP/VMA ratio significantly increased the height due to enhanced yield stress and thixotropy. [ABSTRACT FROM AUTHOR]

The present work investigates the impact of particle size reduction of traditional ceramic materials as partial substitutes for Portland cement in mortars. Ceramic brick, ceramic tile, and stoneware were selected, with three particle sizes (D50 of 1, 5, and 15 μm) achieved through grinding operations adapted to each material grindability. The reactivity of ceramic powders was assessed via dissolution in saturated lime solution. Mortars were prepared with 10 % and 20 % cement mass replaced by ceramic powders ground to each fineness. The packing density of mortars was evaluated using the Compressible Packing Model. Compressive strength was measured at 1, 3, 7, and 28 days, and pore size distribution was analyzed by mercury intrusion porosimetry. Results indicated that ceramic tile required less grinding energy than brick and stoneware. High-energy grinding slightly altered the crystalline structure and increased amorphous content, enhancing reactivity with lime. Increased cement replacement with finer ceramic powders (D50 about 1 μm) improved strength, increased mesopores (50 nm), and reduced pore size threshold, attributed to filler and pozzolanic effects. A multiple linear regression model effectively described the influence of various variables on mortar strength with the interaction terms demonstrating the complexity of the interplay of the variables.

Abstract System design is a challenging and time-consuming task which often requires close collaboration between several multidisciplinary design teams to account for complex interactions between components and sub-systems. As such, there is a growing demand in industry to create better performing, efficient, and cost-effective development tools to assist in the system design process. Additionally, the ever-increasing complexity of systems today often necessitates a shift away from manual expertise and a movement towards computer-aided design tools. This work narrows the scope of the system design process by focusing on one critical design aspect: the packaging of system components. The algorithm presented in this paper was developed to optimize the packaging of system components with consideration of practical, system-level functionalities and constraints. Using a dynamic acceleration methodology, the algorithm packages components from an initial position to a final packed position inside of a constrained volume. The motion of components from initial to final positions is driven by several acceleration forces imposed on each component. These accelerations are based on physical interactions between components and their surrounding environment. Various system-level performance metrics such as center of mass alignment and rotational inertia reduction are also considered throughout optimization. Results of several numerical case studies are also presented to demonstrate the functionality and capability of the proposed packaging algorithm. These studies include packaging problems with known optimal solutions to verify the efficacy of the algorithm. Finally, the proposed algorithm was used in a more practical study for the packaging of an urban air mobility nacelle to demonstrate the algorithm’s prospective capabilities in solving real-world packaging problems.

Purpose To compare the embolization effects of a non-fibered pushable coil with a conventional fibered pushable coil in an in vitro bench-top experiment. Materials and Methods A simplified vascular phantom with 4 channels (1 for the non-fibered coil, 1 for the fibered coil, and 2 for continuous circuit flow) was used. A single coil of the longest length was inserted to evaluate the effect of single-coil embolization, and 3 consecutive coils were inserted to assess the effect of multiple-coil embolization. Post-embolization angiography was performed to obtain flow variables (time to peak [TTP], relative peak intensity [rPI], and angiographic flow reduction score [AFRS]) from time density curves. The packing densities of the two coil types were calculated, and the AFRS of each channel was determined by dividing the TTP by the rPI. Results When inserting a single coil, the conventional fibered coil demonstrated better flow reduction, as indicated by a higher AFRS (25.6 vs. 17.4, P=0.034). However, the non-fibered coil exhibited a significantly higher packing density (12.9 vs. 2.4, P=0.001). Similar trends were observed with multiple coils. Conclusion The conventional fibered pushable coil showed better flow reduction efficiency, while the non-fibered pushable coil had a higher packing density, likely due to the flexibility of the coil loops. A better understanding of the distinct characteristics of different pushable coils can enhance the outcomes of various vascular embolization.

Over the past few decades, enhancing the sustainability of concrete structures has become a worldwide necessity. This study proposes a mathematical model for predicting compressive strength (CS), aiming to further the objective of designing sustainable concretes incorporating silica-fume as a partial cementing replacement material. The article outlines the formulation, calibration, evaluation and validation of the proposed model. Various factors related to concrete mixture and age were considered in the formulation of the CS model, which employed multiple sub-models including a cement hydration model that considers cement chemical composition and hydration rate, along with other factors like aggregate packing density, capillary porosity, air pores, standard cement strength, paste-to-aggregate bond strength and presence of supplementary cementing materials. An experimental program consisting of 10 different concrete mixtures was designed to calibrate and evaluate the model. The model was then validated using databases from multiple literature sources, which consisted of 50 data points with diverse materials and mixture proportions, to test its accuracy and generalization capability. Results show that the proposed model closely matches the experimental data and has no sign of anomalies or distinct trends. The model’s coefficient of determination and standard error are 0.97 and 4.0 MPa, respectively. Moreover, model validation demonstrates high predictability and generalization capability, with a corresponding coefficient of determination and standard error of 0.93 and 4.4 MPa, respectively. Overall, this research suggests that the proposed mathematical model is a reliable tool to predict the CS of sustainable concretes that utilize silica-fume as a partial cementing replacement material.

Hydration of cement materials is accompanied by the formation of calcium silicate hydrates (CSH). Accordingly, the hydration process is completed in the early, middle, and late periods, leading to the formation of two types of CSH phases: of low density (LD) and high density (HD). Usually, under normal conditions, LD CSH is formed in the middle period, while the formation of HD CSH predominates in the later stage. In using the nanoindentation method, it becomes possible to explain the nanogranular nature of the CSH gel, which is characterized by the contact forces of the CSH gel particles for these phases. Studies of cement stone samples at W/C = 0.21 and at the content of hydrothermal SiO2 nanoparticles in the combined additive 0.000006 wt.% and multilayer carbon nanotubes (MCNT) 0.00004 wt.% for cement showed that the effect of nanoparticles on the structure of the CSH gel becomes more pronounced, since the volume fraction of the LD phase of the CSH gel with a low packing density of nanogranules becomes significantly lower than the fraction of the HD phase with increased hexagonal packing density of nanogranules. [ABSTRACT FROM AUTHOR]

In this investigation, four types of sands as alternatives to river sand, namely, crushed sand (CS), marine sand, fine recycled concrete aggregate (FRCA), and fine reclaimed asphalt pavement (FRAP), were studied for their potential for cement-concrete pavement applications. Initially, the physicochemical and morphological characteristics of these sands were understood and later linked to the hydration kinetics and the behavior of cement-mortar systems in both the fresh and hardened states. Due to their evenly graded particle size distribution, CS and FRCA exhibited higher packing densities despite having more gradient angularity, whereas the interlocking capacity of FRAP was found to be affected by the agglomerated particles. Morphology, fineness modulus, and chemical composition of the sands were observed to be the dominating parameters affecting the hydration kinetics and thus the performance of the mortar mixes. Improving these parameters, especially the grain size distribution, could help in enhancing the potential of these sands for pavement applications. [ABSTRACT FROM AUTHOR]

System design is a challenging and time-consuming task which often requires close collaboration between several multidisciplinary design teams to account for complex interactions between components and sub-systems. As such, there is a growing demand in industry to create better performing, efficient, and cost-effective development tools to assist in the system design process. Additionally, the ever-increasing complexity of systems today often necessitates a shift away from manual expertise and a movement towards computer-aided design tools. This work narrows the scope of the system design process by focusing on one critical design aspect: the packaging of system components. The algorithm presented in this paper was developed to optimize the packaging of system components with consideration of practical, system-level functionalities and constraints. Using a dynamic acceleration methodology, the algorithm packages components from an initial position to a final packed position inside of a constrained volume. The motion of components from initial to final positions is driven by several acceleration forces imposed on each component. These accelerations are based on physical interactions between components and their surrounding environment. Various system-level performance metrics such as center of mass alignment and rotational inertia reduction are also considered throughout optimization. Results of several numerical case studies are also presented to demonstrate the functionality and capability of the proposed packaging algorithm. These studies include packaging problems with known optimal solutions to verify the efficacy of the algorithm. Finally, the proposed algorithm was used in a more practical study for the packaging of an urban air mobility nacelle to demonstrate the algorithm's prospective capabilities in solving real-world packaging problems. [ABSTRACT FROM AUTHOR]

Dump slope is mainly attributed to the deep excavation of a mine. In the present work, the dump in Kunyang phosphate mine located in Sanjia Village was investigated. The geographic and geologic settings were first studied according to the field investigation. Aiming at the actual dump scenario, a rainfall system was designed to simulate the process of dump instability induced by rainfall. The novelty lies in conducting comprehensive tests on fundamental parameters, including water content, particle size, compactness, and engineering mechanical properties, through analogous simulation experiments. In addition, the SLIDE software was adopted to analyse the dumps in each mining area and subsequently determine the sliding disaster mode of the dumps in Kunyang phosphate mine. The comparative analysis of the dumps in these different mining areas showed that the dump in No. 6 mining area has a greater factor of safety (FS) and better stability (instability will not occur). Secondly, the stability of the dumps in No. 2, No. 3 and No. 4 is better than that in No. 5, but they have not reached the ultimate equilibrium state (instability will not occur). Nevertheless, the FS of the dump in No. 1 mining area approached or even fell below 1. Thus, it is predicted that a small‐scale landslide disaster may have occurred (instability). Moreover, the dynamic evolution characteristics of dump disasters with different accumulation densities were revealed by model device tests. Finally, the obvious tube surge phenomenon before sliding was observed. [ABSTRACT FROM AUTHOR]

Purpose: To compare the embolization effects of a non-fibered pushable coil with a conventional fibered pushable coil in an in vitro bench-top experiment. Materials and Methods: A simplified vascular phantom with 4 channels (1 for the non-fibered coil, 1 for the fibered coil, and 2 for continuous circuit flow) was used. A single coil of the longest length was inserted to evaluate the effect of single-coil embolization, and 3 consecutive coils were inserted to assess the effect of multiple-coil embolization. Post-embolization angiography was performed to obtain flow variables (time to peak [TTP], relative peak intensity [rPI], and angiographic flow reduction score [AFRS]) from time density curves. The packing densities of the two coil types were calculated, and the AFRS of each channel was determined by dividing the TTP by the rPI. Results: When inserting a single coil, the conventional fibered coil demonstrated better flow reduction, as indicated by a higher AFRS (25.6 vs. 17.4, P=0.034). However, the non-fibered coil exhibited a significantly higher packing density (12.9 vs. 2.4, P=0.001). Similar trends were observed with multiple coils. Conclusion: The conventional fibered pushable coil showed better flow reduction efficiency, while the non-fibered pushable coil had a higher packing density, likely due to the flexibility of the coil loops. A better understanding of the distinct characteristics of different pushable coils can enhance the outcomes of various vascular embolization. [ABSTRACT FROM AUTHOR]

To investigate the effects of the combined addition of Lactiplantibacillus plantarum and sucrose on the fermentation weight loss (FWL), fermentation quality, and microbial community structure of ensiled rape straw under varying packing density conditions. After harvesting, the rapeseed straw was collected, cut into 1–2 cm pieces, and sprayed with sterile water to adjust the moisture content to 60%. The straw was then divided into two groups: one treated with additives (1 × 105 CFU/g fresh material of Lactiplantibacillus plantarum and 10 kg/t fresh material of sucrose), and the other sprayed with an equivalent amount of sterile water as the control (CK). The treated materials were thoroughly mixed and packed into silos at densities of 450, 500, and 550 kg/m3. FWL was recorded on days 1, 3, 6, 15, 20, and 45 of fermentation. On day 45, the samples were analyzed for fermentation quality, microbial counts, and microbial diversity. FWL increased significantly (p < 0.05) in both the treated (LS) and control groups during fermentation. The LS group showed higher lactic acid (LA) levels (p < 0.05) and lower ammonia nitrogen levels (p < 0.05) compared to CK. The CK group had significantly higher (p < 0.05) counts of Coliforms and lower bacterial counts (p < 0.05) than LS. The dominant genera in the silage were Xanthomonas, Lactiplantibacillus plantarum, and Lentilactobacillus. In the LS group, the relative abundances of Lactiplantibacillus plantarum and Lentilactobacillus ranged from 16.93% to 20.43% and 15.63% to 27.46%, respectively, with their combined abundance being higher than in CK. At a packing density of 500 kg/m3, the relative abundances of Lactiplantibacillus plantarum and Lentilactobacillus in the LS group were significantly higher (p < 0.05) than in CK. Increasing packing density and applying additives to rape straw silage effectively reduced FWL, improved fermentation quality, boosted the relative abundance of beneficial lactic acid bacteria, and decreased the presence of undesirable bacteria such as Enterobacter and Bacillus.

Ultra-high-performance concrete (UHPC) is a high-tech concrete whose excellent mechanical and durability characteristics are ascribed to the homogeneity and high packing density of its matrix. However, due to the high contents of cement and silica fume usually necessaries for achieving this packing density, UHPC's final cost and carbon-footprint are far higher than standard concretes. Therefore, over the last few years, the spotlight of UHPC's research has focused sharply on the analysis of locally available supplementary cementitious materials as partial replacement of cement and silica fume. This article presents an investigation to analyze the effect of rice husk ash (RHA) as partial substitution of cement in a previously optimized mixture of recycled-glass-UHPC by means of several statistical tools. Cementitious materials employed in this research involved silica fume, limestone powder, recycled glass powder and ordinary Portland cement (OPC). Based on the results, it can be concluded that RHA addition in the optimized glass UPHC yields to a significant decrease in the workability of concrete and a slight decrease of compressive strength. Results also demonstrated the high interaction between the RHA and water contents, which could be ascribed to the water absorption and internal curing provided by RHA particles. [ABSTRACT FROM AUTHOR]

This study investigates the interplay between particle shape, grading and initial sample density, three of the most important factors influencing the mechanical behaviour of sheared granular assemblies. Using the discrete element method (DEM), two-dimensional assemblies of varying initial sample density, particle aspect ratio, AR , and coefficients of uniformity, C u , were prepared and subjected to drained biaxial shearing until the critical state was reached. We assessed the interplay between each of these parameters by evaluating whether the effect of any given parameter on a mechanical quantity is influenced by any other parameter. Our analyses show that the effect of some of these key parameters on mechanical response, can indeed be influenced by other key parameters. The effect of the particle AR on the peak shear strength for the initially dense assemblies differs when compared with the medium-dense assemblies. The mechanical coordination number of the assemblies at the initial state correlates with the peak strength thereby explaining the interplay between particle AR and initial sample density on the peak shear strength. The linear relationship established between strength and dilatancy for a combination of all assemblies studied suggests that the strength-dilatancy relationship is a unique characteristic of granular assemblies. The dilatancy of the assemblies correlates strongly with the amount of contacts lost during shearing. The interplays found between particle shape, grading and initial sample density in this study show that to develop robust constitutive models for the prediction of granular material behaviour, the effects of multiple factors must be considered. [ABSTRACT FROM AUTHOR]

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The objective of this research is to develop an innovative methodology for evaluating the quality of coarse aggregate mixes that incorporate recycled concrete aggregate for use in structural concrete. The proposed approach consists of three steps: measuring the packing density, quantifying the adhered mortar, and characterizing the mechanical resistance of the aggregate mixes containing both natural and recycled concrete aggregate. Comprehensive practical recommendations for each step are discussed in detail to facilitate the broader future utilization of recycled concrete aggregate in structural concrete. The mechanical resistance of aggregate mixes is significantly influenced by both packing density and the quantity of adhered mortar. Predictive models are used to illustrate the mechanical resistance of aggregate mixes based on packing density and adhered mortar amount, recognizing the direct correlation between these properties. [ABSTRACT FROM AUTHOR]

Crystal structure determines electrochemical energy storage characteristics; this is the underlying logic of material design. To date, hundreds of electrode materials have been developed to pursue superior performance. However, it remains a great challenge to understand the fundamental structure-performance relationship and achieve quantitative crystal structure design for efficient energy storage. In this review, we introduce the concept of crystal packing factor (PF), which can quantify crystal packing density. We then present and classify the typical crystal structures of attractive cathode/anode materials. Comparative PF analyses of different materials, including polymorphs, isomorphs, and others, are performed to clarify the influence of crystal packing density on energy storage performance through electronic and ionic conductivities. Notably, the practical electronic/ionic conductivities of energy storage materials are based on their intrinsic characteristics related to the PF yet are also affected by extrinsic factors. The PF provides a novel avenue for understanding the electrochemical performance of pristine materials and may offer guidance on designing better materials. Additional approaches involve size regulation, doping, carbon additives, and other methods. We also propose extended PF concepts to understand charge storage and transport behavior at different scales. Finally, we provide our insights on the major challenges and prospective solutions in this highly exciting field. [ABSTRACT FROM AUTHOR]

Due to a shortage of river sand for concrete production, manufactured sand (MS) made from crushed rock has gradually become a substitute. It inherently contains some fines content, which has significant effects on the performance of concrete. To study the effects of the MS type and fines content on the workability, cohesiveness, and strength, concrete mixes made with granite MS or limestone MS and different fines contents at various water/binder ratios were tested. Moreover, the packing density, water film thickness (WFT), paste film thickness (PFT), and microstructures of the concrete mixes produced were examined to investigate if their changes were the root causes of the effects of the MS used. It was found that the use of granite MS attained higher workability and strength but lower cohesiveness, which apparently were caused by the higher packing density and larger WFT and PFT. Also, regardless of the MS type, a fines content of about 10% was the optimum for highest packing density and best concurrent workability-cohesiveness-strength performance. Correlation analysis revealed that the MS and fines content exerted their influences on the workability and cohesiveness through the WFT and PFT, and on the strength through the packing density and microstructure. [ABSTRACT FROM AUTHOR]

Over the past few decades, enhancing the sustainability of concrete structures has become a worldwide necessity. This study proposes a mathematical model for predicting compressive strength (CS), aiming to further the objective of designing sustainable concretes incorporating silica-fume as a partial cementing replacement material. The article outlines the formulation, calibration, evaluation and validation of the proposed model. Various factors related to concrete mixture and age were considered in the formulation of the CS model, which employed multiple sub-models including a cement hydration model that considers cement chemical composition and hydration rate, along with other factors like aggregate packing density, capillary porosity, air pores, standard cement strength, paste-to-aggregate bond strength and presence of supplementary cementing materials. An experimental program consisting of 10 different concrete mixtures was designed to calibrate and evaluate the model. The model was then validated using databases from multiple literature sources, which consisted of 50 data points with diverse materials and mixture proportions, to test its accuracy and generalization capability. Results show that the proposed model closely matches the experimental data and has no sign of anomalies or distinct trends. The model's coefficient of determination and standard error are 0.97 and 4.0 MPa, respectively. Moreover, model validation demonstrates high predictability and generalization capability, with a corresponding coefficient of determination and standard error of 0.93 and 4.4 MPa, respectively. Overall, this research suggests that the proposed mathematical model is a reliable tool to predict the CS of sustainable concretes that utilize silica-fume as a partial cementing replacement material. [ABSTRACT FROM AUTHOR]

Fly ash is a fine powdery particle collected from the unit operations of coal combustion furnaces in thermal power plants. Retained fly ash at bottom of hopper has been mixed with water and dumped in lagoons in form of slurry as pond ash (PA) or lagoon ash. Ground Granulated Blast Furnace Slag (GGBS) is a by-product obtained from steel industry. In this study, three phase of concrete specimens were prepared. In first phase, the specimens were prepared using 100% cement with various water-to-cementitious ratios. In second phase, specimens were prepared with varying water-tocementitious ratios and PA contents ranging from 0 to 20%. Finally, the third phase, specimens were prepared to determine the optimal PA content, with GGBS ranging from 0 to 25%. The mechanical and rheological properties of different proportions of PA and GGBS have been experimentally investigated at 28 days. In addition, the flow ability and packing density of different proportions of PA and GGBS various mixes were tested. The test results revealed that combination of PA and GGBS up to 27% would enhance the fresh and harden properties of cementitious material. The rheological behaviour of optimal PA and GGBS concrete were tested at 28 days using scanning electron microscope (SEM). The results confirmed that the addition of PA and GGBS resulting in a denser, less porous, and more compact CSH microstructure in concrete. [ABSTRACT FROM AUTHOR]

The one-to-one contact of coarse aggregate is considered to be the main source for the resistance to permanent deformation and to an extent to fatigue damage. Therefore, it is imperative that the mixture is placed with an interlocked coarse-aggregate skeleton. The conventional mix design approaches generally follow dense graded aggregate gradations, which target for maximum density without accounting the one-to-one contact of coarse aggregates. The current study describes an approach for analysing particle packing in bituminous mixtures based on the compressible packing model (CPM), which provides an analytical expression for the estimation of aggregate packing density. Three mixtures with chosen particle packing indicators and a conventional dense graded mixture are subjected to repeated load haversine compression at temperatures between 25 $^{\circ }$ ∘ and 55 $^{\circ }$ ∘ for a frequency range of 0.01–25 Hz. Selection of binder content is carried out based on equivalent compactability criteria. The link between the packing density of aggregate gradation, dynamic modulus, phase angle, master curve parameters, and relaxation spectrum is evaluated in this study. It is observed that dynamic modulus at high temperature, and low frequency, the phase angle, master curve parameters and the relaxation spectrum exhibit sensitivity to the variation in aggregate gradation. [ABSTRACT FROM AUTHOR]

This article demonstrates the effect of varying the maximum grain size and the layer thickness of the particle bed on hardened state properties in Selective Cement Activation (SCA). The compressive strength and geometry (deviation from nominal geometry, surface roughness) are analyzed. Supplementary investigations (μCT, μRFA) are performed to explain the causes of the observed effects. It is found that the compressive strength of the manufactured specimens increases with decreasing layer thickness. This is attributed to reduced process‐induced segregation of the particle bed and fewer process‐induced voids. The geometric precision as well as the surface roughness of the printed test specimens do not differ significantly. As the grain size increases, the amount of compaction required to achieve the target packing density decreases. The compressive strength was found to increase when the grain size in the specimen is reduced. As the finer particle mixtures tend to have less void formation as a result of water application, an increased density of the specimen can be observed. The lower porosity as well as the smaller pores also have a favorable effect on geometric precision, which tends to increase with reduced grain size. At the same time, a lower surface roughness is also present. [ABSTRACT FROM AUTHOR]

Self-compacting concrete (SCC), known for its excellent fluidity and self-compacting ability, is widely used in civil engineering. To enhance the comprehensive performance of SCC, dolomite powder (DP) is integrated as a substitute for cement. This study aims to analyze the impact of DP on the yield stress relationship between self-compacting mortar (SCM) and self-compacting paste (SCP) from a multi-scale perspective. A new predictive model for the yield stress relationship between SCM and SCP incorporating DP is established by improving the n value in the existing ϕe model, which characterizes the sensitivity of the mortar yield stress relative to changes in the paste yield stress. By conducting mini-slump flow tests on nine sets of cement–DP mixtures, it is found that DP impacts the yield stress relationship between SCM and SCP mainly through changes in the inter-particle filling effect, and the n value in the predictive model is roughly between 2.4 and 3.6. When the DP content is kept constant and the particle size is changed, the n value shows a strong positive linear relationship with the packing density of the paste (ϕe,p). The relationship between n and ϕe,p is derived using the linear fitting method, which improves the model’s predictive accuracy by 95.2%.

Sustainability and limitations in embedded reinforcement are the main obstacles in digital fabrication with concrete. This study proposed a 3D printable fiber-reinforced calcined clay-limestone-based cementitious material (FR-LC3). The binder systems incorporating calcined clay (CC) and limestone filler (LF) were optimized by determining the flow characteristics and water retention ability of the paste. The effect of fiber volume on the key fresh and mechanical properties of the fiber-reinforced mortars made with the optimized binder was evaluated. A combination of offline assessments and inline printing were employed to investigate the printability of the FR-LC3 with various binder systems and viscosity-modifying admixture (VMA) dosages. The results revealed that the binary system with 20% CC and the ternary system containing 30% CC and 15% LF were highly advantageous, with enhanced packing density, robustness, and water retention ability. Incorporating 2% 6-mm steel fiber contributed to the highest 28-day compressive and flexural strengths and toughness without significantly compromising the fluidity. Finally, the developed FR-LC3 mixtures were successfully printed using an extrusion-based 3D printer. The LF addition in the ternary system decreased the maximum buildable height of a single-wall printed object while reducing the SP/VMA ratio significantly increased the height due to enhanced yield stress and thixotropy.

In this study, the influence of fine aggregate's grading on mortar's rheology is investigated. Firstly, the non-uniformity coefficient (Cu) and the coefficient of curvature (Cc) were employed to quantitatively evaluate the fine aggregate's grading. The results show that Cu provides a good quantitative description of the fine aggregate's grading and presents a good correlation with its packing density. Following that, the influence of the fine aggregate's grading on mortar's rheology was quantitatively analysed using the Cu parameter, and it was found that the higher the Cu value, the lower the relative yield stress (τr) and relative plastic viscosity (μr) of the corresponding mortar. In addition, the rate of variation of τr and μr with respect to Cu is very small after exceeding a critical value (4.85). This study suggests that, for a packing density higher than a critical value (0.7391), it may be more effective to improve the rheology of mortar by acting on aspects other than the fine aggregate's grading.

Floating catalysis chemical vapor deposition (FCCVD) direct spinning process is an attractive method for fabrication of carbon nanotube fibers (CNTFs). However, the intrinsic structural defects, such as entanglement of the constituent carbon nanotubes (CNTs) and inter-tube gaps within the FCCVD CNTFs, hinder the enhancement of mechanical/electrical properties and the realization of practical applications of CNTFs. Therefore, achieving a comprehensive reassembly of CNTFs with both high alignment and dense packing is particularly crucial. Herein, an efficient reinforcing strategy for FCCVD CNTFs was developed, involving chlorosulfonic acid-assisted wet stretching for CNT realigning and mechanical rolling for densification. To reveal the intrinsic relationship between the microstructure and the mechanical/electrical properties of CNTFs, the microstructure evolution of the CNTFs was characterized by cross-sectional scanning electron microscopy (SEM), wide angle X-ray scattering (WAXS), polarized Raman spectroscopy and Brunauer–Emmett–Teller (BET) analysis. The results demonstrate that this strategy can improve the CNT alignment and eliminate the inter-tube voids in the CNTFs, which will lead to the decrease of mean distance between CNTs and increase of inter-tube contact area, resulting in the enhanced inter-tube van der Waals interactions. These microstructural evolutions are beneficial to the load transfer and electron transport between CNTs, and are the main cause of the significant enhancement of mechanical and electrical properties of the CNTFs. Specifically, the tensile strength, elastic modulus and electrical conductivity of the high-performance CNTFs are 7.67 GPa, 230 GPa and 4.36 × 106 S/m, respectively. It paves the way for further applications of CNTFs in high-end functional composites. [ABSTRACT FROM AUTHOR]

It is known that optimum packing of coarse and finer fractions in grading of aggregates has proved to improve the mechanical, durability and sustainable properties of concretes. In the present work, composite cement (CC) prepared by interblending of fly ash (FA) and granulated blast furnace slag (GBFS) with ordinary Portland cement (OPC) was used to prepare four grades of CC concretes, viz. M20, M30, M40 and M50, based on guidelines recommended by three international standards, viz. Indian Standard 10262:2019 (IS), American Concrete Institute 211.1-91:2000 (ACI), British Standard 8500-2:2015 (BS) and the reference modified Andreassen model (MAM) through ideal packing curves. The main aim of this study is to establish the influence of ideal gradation of total particulate matrix of concrete constituents on fresh, mechanical and sustainable properties of concretes. In the design of MAM-based concrete mixes, the total particulate matter comprising of coarse aggregates, fine aggregates, cement, FA and GBFS was optimized to match the ideal packing curves of MAM. The particle size distribution curves obtained for total particulate matrix of four grades of concretes designed as per IS, ACI and BS are compared with ideal packing curves of MAM. The concrete mixes designed as per MAM showed better sustainable properties and comparable mechanical properties with respect to concrete mixes designed using other international standards. [ABSTRACT FROM AUTHOR]

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The effect of graphene (GR) on Ni surface relaxation and reconstruction in three different substrate orientations, {111}, {001}, and {011}, at two different temperatures, 300 K and 400 K, was studied using molecular dynamics simulation. The change in the interplanar distances of the substrate and redistribution of Ni and C atoms in a direction perpendicular to the surface was compared with the equilibrium state of GR and bulk Ni, in the absence of the counterpart. The surface reconstruction for the GR/Ni system was analyzed based on the calculated radial pair distribution functions of Ni and C atoms. The surface roughness was visualized using 2D atomic distribution maps. The introduction of GR on the Ni surface in any crystallographic orientation decreases the maximum modification of interplanar spacing compared to the bulk by less than 1%. For the studied substrate orientations and temperatures, it was found that the most densely packed {111} orientation of the Ni base provides minimal changes in the structural parameters of both counterparts at 400 K. Additionally, the system formed by GR deposition on Ni {111} at 400 K is characterized by the least roughness. [ABSTRACT FROM AUTHOR]

False twisting has been used to reduce yarn twists while keeping yarn tenacity, which is vital to improve fabric softness. In this paper, a false twisting device was integrated into a siro spinning system to develop a novel yarn structure with enhanced softness, in which the fibers were uniformly arranged. Siro false twist spun yarn was compared with a conventional siro spun yarn with the same count and twist in terms of yarn diameter, tenacity, hairiness, evenness, and packing density. The cross-sectional packing density of the yarns was analyzed based on micro X-ray computed tomography. The results showed that the siro false twist spun yarn has advantages in hairiness and evenness. The siro false twist spun yarn has an increased diameter by 10.4–19.0% and a more uniform cross-sectional packing density than the siro spun yarn. The two yarns were knitted into fabrics, and test results showed that the fabric produced with the siro false twist spun yarns had better compressibility, air permeability and light transmission. The findings from this study demonstrated that the siro false twist spun yarn improved fullness and its fabric has superior softness. [ABSTRACT FROM AUTHOR]

Concrete is by a substantial margin the most widely used construction material. Projections indicate that the demand for concrete it will continue to increase to sustain the development of emerging economies. This paper presents a new perspective of low-carbon concrete by refocusing on the actual final product, highlighting the tremendous CO2 saving opportunities of reducing the total paste volume of concrete while simultaneously using high performance, low-clinker cements in the so-called two-fold strategy (low clinker content, low paste volume concrete formulations). Different aspects of low paste volume concrete formulations are discussed based on a combination of published and new concrete performance data, showing the potential for CO2 savings of the strategy and the technical opportunities to retain the robustness and reliability that make concrete such a versatile and widely used material. Chemical admixtures play a crucial role in reaching those objectives, as they enable to reduce the cement content while retaining the needed workability (slump and slump retention) for each application. The key issues relating to using those admixtures in low carbon concrete are highlighted.

Thin HfO2 films atomic layer deposited from hafnium alkyl amide and oxygen plasma were analysed using spectroscopic ellipsometry and X-ray reflectivity. Low refractive index of the material for samples with less than 30 nm thickness marks the index inhomogeneity at the first stage of growth. The transition from rising density to a more stable growth takes place at about 10 to 25 nm film thickness. HfO2 films used for resistive switching experiments demonstrate either clockwise or counterclockwise behaviour depending on the film thickness. The reason for this may be the disruption of the conductive filament at different metal-insulator interfaces, which could be favoured by several mechanisms. [ABSTRACT FROM AUTHOR]

A requirement for achieving sustainable concrete structures is to develop a quantitative method for designing concrete mixtures that yields the target rheological properties and compressive strength. Toward this objective, this paper proposes a mathematical model approach to improve the sustainability of the concrete industry. A postulation that packing density, a function of the concrete mixture, provides the link between concrete mixture, rheological properties, and compressive strength was investigated. Rheological models for yield stress and plastic viscosity, and a compressive strength model were adopted with packing density as a central variable. The rheological models employ a cell description that is representative of fresh concrete. The compressive strength model is based on excess paste theory to account for the concrete mixture proportions, gradation of aggregate particles, and porosity. An experimental program was developed to calibrate and test these models. Results revealed that packing density provides a consistent and reliable link, and that the concrete mixture composition can be designed to achieve the target rheological properties and hardened properties and ensure quality control. Consequently, a new mixture proportioning methodology was developed and proposed as an improvement to the ACI 211.1 mixture design method. Furthermore, a case study was conducted to test for the applicability and adequacy of this proposed method. This research outcome, which provides a quantitative approach to design concrete mixtures to meet specific strength requirements and rheology, can also be used to ensure quality control before concrete is cast. [ABSTRACT FROM AUTHOR]

In Szirmai (Ars Math Contemp 16:349–358, 2019) we proved that to each saturated congruent hyperball packing there exists a decomposition of the 3-dimensional hyperbolic space H 3 into truncated tetrahedra. Therefore, in order to get a density upper bound for hyperball packings, it is sufficient to determine the density upper bound of hyperball packings in truncated simplices. In this paper we prove, using the above results and results of the papers Miyamoto (Topology 33(4): 613–629, 1994) and Szirmai (Mat Vesn 70(3): 211–221, 2018), that the density upper bound of the saturated congruent hyperball (hypersphere) packings related to the corresponding truncated tetrahedron cells is realized in regular truncated tetrahedra with density ≈ 0.86338 . Furthermore, we prove that the density of locally optimal congruent hyperball arrangement in a regular truncated tetrahedron is not a monotonically increasing function of the height (radius) of the corresponding optimal hyperball, unlike the ball (sphere) and horoball (horosphere) packings. [ABSTRACT FROM AUTHOR]