Packing Characteristics Research Articles

Optimizing Designs of Structurally Stable Open-graded Aggregate Bases (OGAB) in Concrete Pavements

A stable, non-erodible, drainable base layer is crucial to maintain uniform support under concrete pavements and ensure satisfactory performance. This paper presents findings from a recent study aimed at investigating possible improvements in concrete pavement base layers in terms of stability, stiffness, and permeability. Moisture regimes in PCC pavement foundation layers and corresponding predicted pavement performance were first evaluated using different types of base course materials with varying hydraulic and mechanical properties. A previously validated discrete element method (DEM) model was subsequently employed for evaluating the gradation effect on both packing characteristics and load-carrying performance of unbound aggregate materials. The calibrated DEM model has the potential for optimizing the selection of size and shape properties of various types of unbound aggregates to achieve desired shear strength (stability) and drainage characteristics (drainability) for open-graded permeable aggregate base. DEM simulations were performed on different gradations chosen from the current Minnesota Department of Transportation (MnDOT) specified gradation band for unbound permeable aggregate base (UPAB). It was found that depending on the specific gradation and material hydraulic properties, different types of unbound permeable aggregate bases resulted in varying performance improvements. The benefits of maintaining adequate permeability and stability of base course proved to be evident. The DEM model simulation results indicated that a gravel to sand (G/S) ratio of 1.6 yielded the highest coordination number due to the achieved densest packing (indicated by the lowest porosity). Therefore, the optimal G/S ratio of 1.6 also determined previously from experimental results agreed well with the results of DEM simulations, which utilized three-dimensional polyhedral particles with realistic size distributions and aggregate shape properties. The use of such optimal size and shape properties is expected to achieve cost-effective open-graded aggregate base designs for long-life concrete pavements.

Effects of feed flow rate on the random packing characteristics and contact heat transfer characteristics of thermal energy storage particle piles for renewable energy systems

Effects of feed flow rate on the random packing characteristics and contact heat transfer characteristics of thermal energy storage particle piles for renewable energy systems

Impact of the feed particle size distribution and its packing characteristics on compression comminution

Due to its lower energy consumption than a conventional grinding circuit, there is an increased interest in the mining industry in the High-Pressure Grinding Rolls (HPGR) technology. Despite the benefits, the high quantity of material required to size the HPGR makes it difficult for new mines to consider this technology. The piston press test has been used at The University of British Columbia to predict the behavior of the HPGR. It is possible to predict energy requirements, size reduction, and throughput by utilizing a small amount of material to size the HPGR. The bulk material’s particle size distribution (PSD) plays an important role in how the particle bed will pack. This study investigates the differences in compressing three different sample PSDs obtained from the same copper ore crushed to −12.5 mm. The first PSD corresponds to the natural distribution resulting from the crusher. The second is created artificially to match the Fuller curve PSD, which theoretically should have the highest packing density. The third corresponds to a truncated feed produced by removing the fines (−300μm) from the natural feed. Tests were performed using a piston-and-die press test apparatus to compress the samples at different force levels. Entirely different behaviors are obtained while compressing the same material with different PSDs. Particularly, the Fuller curve PSD achieves a 31%–40% higher grinding rate than the natural feed, while the truncated feed achieves a 9%–30% higher grinding rate than the natural feed. Differences in the specific energy consumption, grinding efficiency, and final compacted densities highlight the critical influence of feed particle size distribution on the energy usage and generation of fine particles, underscoring the importance of optimizing these parameters for energy-efficient mineral processing. The overall findings indicate that an HPGR feed particle size distribution that matches the Fuller curve and, therefore, has a maximum packing density, results in the most energy-efficient comminution.

Investigating the impact of 2-OHOA-embedded liposomes on biophysical properties of cancer cell membranes via Laurdan two-photon microscopy imaging

2-Hydroxyoleic acid (2-OHOA) has gained attention as a membrane lipid therapy (MLT) anti-cancer drug. However, in the viewpoint of anti-cancer drug, 2-OHOA shows poor water solubility and its effectiveness still has space for improvement. Thus, this study aimed to overcome the problems by formulating 2-OHOA into liposome dosage form. Furthermore, in the context of MLT reagents, the influence of 2-OHOA on the biophysical properties of the cytoplasmic membrane remains largely unexplored. To bridge this gap, our study specifically focused the alterations in cancer cell membrane fluidity and lipid packing characteristics before and after treatment. By using a two-photon microscope and the Laurdan fluorescence probe, we noted that liposomes incorporating 2-OHOA induced a more significant reduction in cancer cell membrane fluidity, accompanied by a heightened rate of cellular apoptosis when compared to the non-formulated 2-OHOA. Importantly, the enhanced efficacy of 2-OHOA within the liposomal formulation demonstrated a correlation with its endocytic uptake mechanism. In conclusion, our findings underscore the significant influence of 2-OHOA on the biophysical properties of cancer plasma membranes, emphasizing the potential of liposomes as an optimized delivery system for 2-OHOA in anti-cancer therapy.

Accurate Density Prediction of Sesquiterpenoid HEDFs and the Multiproperty Computing Server SesquiterPre.

Accurate and rapid evaluation of density is crucial for evaluating the packing and combustion characteristics of high-energy-density fuels (HEDFs). This parameter is pivotal in the selection of high-performance HEDFs. Our study leveraged a polycyclic compound density data set and quantum chemical (QC) descriptors to establish a correlation with the target properties using the XGBoost algorithm. We utilized a recursive feature elimination method to simplify the model and developed a concise and interpretable density prediction model incorporating only six QC descriptors. The model demonstrated robust performance, achieving coefficients of determination (R 2) of 0.967 and 0.971 for internal and external test sets, respectively, and root-mean-square errors (RMSE) of 0.031 and 0.027 g/cm3, respectively. Compared to the other two mainstream methods, the marginal discrepancy between the predicted and actual molecular densities underscores the model's superior predictive ability and more usefulness for energy density calculation. Furthermore, we developed a web server (SesquiterPre, https://sespre.cmdrg.com/#/) that can simultaneously calculate the density, enthalpy of combustion, and energy density of sesquiterpenoid HEDFs, which greatly facilitates the use of researchers and is of great significance for accelerating the design and screening of novel sesquiterpenoid HEDFs.

Measuring cells as a potential tool for the design and retrofit of columns with structured packings

In-depth experiments regarding the separation performance and pressure drop within a novel measuring cell, for the determination of structured packing characteristics for distillation processes, are presented. Furthermore, experiments with a pilot plant column (DN 250) were conducted and compared to the retrieved results from the measuring cell. Additionally, mass transfer coefficients were obtained from the conducted separation performance measurements of the measuring cell through a rate-based model. These coefficients were then used to predict the separation performance of a DN 250 column with an accuracy as good as using the Delft model for the prediction of the mass transfer coefficients. After introducing a maldistribution factor, the prediction of the separation performance of the DN 250 column with the measuring cell mass transfer coefficients could be significantly improved. Changing the packing type within the measuring cell revealed that the measuring cell can give reliable and reproducible results for packings with specific surface areas of 500m2m−3 and 250m2m−3, while at the same time investigating a close boiling system. The presented results indicate that the measuring cell is a promising tool for supporting the retrofit and design of columns with structured packings.

Corroborative studies on chain packing characteristics of biological medium-chain-length poly-3-hydroxyalkanoates with different monomeric composition

Medium-chain-length poly-3-hydroxyalkanoates (mcl-PHAs) with varied monomeric compositions were biosynthesized by producer bacteria fed with different fatty acids as carbon source. Octanoic-, lauric-, stearic-, and oleic acids were used to produce four types of mcl-PHAs viz. PHA-OC, PHA-LA, PHA-ST, and PHA-OL, respectively. The mcl-PHAs as film-casted preparations exhibit distinct traits e.g., PHA-OC and PHA-ST films are less flexible than PHA-LA while PHA-OL is a sticky, glue-like material; PHA-ST is opaque whereas PHA-OC, PHA-LA, and PHA-OL displayed transparent layers. The observation is attributed to polymer chain packing and side chain crystallization. A structure-property investigation of these biopolymers was carried out employing different spectroscopic and microscopic analyses in addition to thermal analyses. Comparative analyses of the results were applied in the interpretation and discussion of structure-property relationship.

Mechanistic enhancement of emulsification function in zein/pectin complex nanoparticles by short linear glucan

The objective of this research was to create stable Pickering emulsions (PEs) by manipulating the structure of the interface through the control of interfacial properties, self-assembly, and packing characteristics of zein particles, utilizing the interaction between short linear glucan (SLG) and pectin. The scientists successfully synthesized ternary complex particles designated as SZPPs (abbreviated for SLG/Zein/Pectin), displaying three-phase contact angles ranging from 83.14° to 87.32°. SZPPs were effectively anchored at the oil-water interface, resulting in a robust and well-organized arrangement, as confirmed by the combination of Langmuir−Blodgett and Scanning Electron Microscope (LB-SEM) and confocal laser scanning microscopy techniques. This arrangement led to the formation of a permeating three-dimensional network of oil droplets, which greatly contributed to the creation of stable PEs. These PEs exhibited unique properties such as viscoelasticity, remarkable thixotropy, and excellent long-term storage stability. One noteworthy advantage of these engineered PEs was their ability to shield curcumin from degradation caused by UV radiation, thereby enhancing the oxidative stability of the emulsions. This protective effect ensures that the curcumin remains intact and active over time. Considering these advantageous properties, these engineered PEs hold great promise for various applications in the food and pharmaceutical industries.

Correlation of the physicochemical, dimensional and packing characteristics with the wear behavior of metal-on-UHMWPE tribological pairs

Correlation of the physicochemical, dimensional and packing characteristics with the wear behavior of metal-on-UHMWPE tribological pairs

Bed expansion in turbulent bed contactor: Experiments and prediction

In this work, turbulent bed contractor (TBC) hydrodynamics have been studied in terms of bed expansion (Hd/Hst) using a particular approach to predict this important property for the design of such equipment. The study is based on 1604 sets of experimental data on the bed expansion, obtained by varying the operating variables (gas velocity, liquid spray, packing characteristics, static bed height, and free opening of the supporting grid). The prediction of the bed expansion necessitates the estimation of gas and liquid holdups. To achieve this, we employed a variety of correlations derived from existing literature, comprising six equations for gas holdup and twenty equations for liquid holdup estimation. Out of a total of 120 cases, bed expansion was estimated, and the accuracy of the model was evaluated by calculating the mean absolute error in percentage (MAPE), root mean square error (RMSE), correlation coefficient (?XY), and explained variance (VECV). This study identified suitable correlations for gas and liquid holdups, leading to predictions with acceptable errors. Furthermore, statistical analysis was employed in a subsequent phase of the study to determine the most appropriate correlations for predicting bed expansion among those proposed by various authors.

Prediction of molecular packing characteristics of two-component crystals

Linear correlation equations linking the β(CC) parameter of the two-component crystals with the similar parameter β(CF2) of the single-component crystal for the strictly fixed temperatures were derived.

Polymorphism-driven Distinct Nanomechanical, Optical, Photophysical, and Conducting Properties in a Benzothiophene-quinoline.

Polymorphic forms of organic conjugated small molecules, with their unique molecular shapes, packing arrangements, and interaction patterns, provide an excellent opportunity to uncover how their microstructures influence their observable properties. Ethyl-2-(1-benzothiophene-2-yl)quinoline-4-carboxylate (BZQ) exists as dimorphs with distinct crystal habits - blocks (BZB) and needles (BZN). The crystal forms differ in their molecular arrangements - BZB has a slip-stacked column-like structure in contrast to a zig-zag crystal packing with limited π-overlap in BZN. The BZB crystals characterized by extended π-stacking along [100] demonstrated semiconductor behavior, whereas the BZN, with its zig-zag crystal packing and limited stacking characteristics, was reckoned as an insulator. Monotropically related crystal forms also differ in their nanomechanical properties, with BZB crystals being considerably softer than BZN crystals. This discrepancy in mechanical behavior can be attributed to the distinct molecular arrangements adopted by each crystal form, resulting in unique mechanisms to relieve the strain generated during nanoindentation experiments. Waveguiding experiments on the acicular crystals of BZN revealed the passive waveguiding properties. Excitation of these crystals using a 532 nm laser confirmed the propagation of elastically scattered photons (green) and the subsequent generation of inelastically scattered (orange) photons by the crystals. Further, the dimorphs display dissimilar photoluminescence properties; they are both blue-emissive, but BZN displays twice the quantum yield of BZB. The study underscores the integral role of polymorphism in modulating the mechanical, photophysical, and conducting properties of functional molecular materials. Importantly, our findings reveal the existence of light-emitting crystal polymorphs with varying electric conductivity, a relatively scarce phenomenon in the literature.

Study on packing characteristics of powders with surface modification by nanoparticles

Powders with coated nanoparticles on the surface as a surface modification technique can alter the surface texture of the particles. This paper explored the additional number of nanoparticles on powder packing characteristics. The adhesion mode of nanoparticles and its influence on the inter-particle force in the system were discussed. The study found that the bulk density first increases and then decreases as the content of nanoparticles increases. The incorporation of nanoparticles reduces the inter-particle force, with the optimal mass fraction of nanoparticles being 0.25%, resulting in a 4.43% increase in bulk density. The attachment mode of nanoparticles was observed and analyzed through SEM, with five possible contact modes between particles identified. The change in the inter-particle force was quantitatively analyzed through the probability of each mode. The Bo number was used to establish a prediction model for bulk density, which yielded a highly accurate prediction.

Optimization of Pore Characteristics of Graphite-Based Anode for Li-Ion Batteries by Control of the Particle Size Distribution

We investigate the reassembly techniques for utilizing fine graphite particles, smaller than 5 µm, as high-efficiency, high-rate anode materials for lithium-ion batteries. Fine graphite particles of two sizes (0.4–1.2 µm and 5 µm) are utilized, and the mixing ratio of the two particles is varied to control the porosity of the assembled graphite. The packing characteristics of the assembled graphite change based on the mixing ratio of the two types of fine graphite particles, forming assembled graphite with varying porosities. The open porosity of the manufactured assembled graphite samples ranges from 0.94% to 3.55%, while the closed porosity ranges from 21.41% to 26.51%. All the assembled graphite shows improved electrochemical characteristics properties compared with anodes composed solely of fine graphite particles without granulation. The sample assembled by mixing 1.2 µm and 5 µm graphite at a 60:40 ratio exhibits the lowest total porosity (27.45%). Moreover, it exhibits a 92.3% initial Coulombic efficiency (a 4.7% improvement over fine graphite particles) and a capacity of 163.4 mAh/g at a 5C-rate (a 1.9-fold improvement over fine graphite particles).

Optimization on the mix design method of self-compacting concrete with recycled coarse aggregate based on paste rheological threshold theory and material packing characteristics

This study aims to use the mixture design method to optimize self-compacting concrete (SCC) and manufacture SCC with excellent workability using recycled coarse aggregate (RCA) and a ternary cementitious system. The influences of incorporated RCA on the rheological thresholds of SCC with a fixed content of fly ash (FA) and blast furnace slag (BFS) are investigated based on paste rheological threshold theory and material packing characteristics. The original rheological model is improved by introducing the volume of adhesive mortar and modifying the equivalent packing density and mortar film thickness. The improved model is incorporated into the original theoretical system to apply the optimized mix design method to SCC. Moreover, experiments are conducted with different volumes of water, water-powder ratios and RCA replacement levels to verify the applicability of the optimized method. The results indicate that the proposed models can accurately predict the yield strength threshold and plastic viscosity threshold of fresh SCC. Furthermore, compared to the original model, predictions are 53% more accurate with the modified model.

Impact of minimum distance constraints on sheet metal waste for plasma cutting.

We approached the two-dimensional rectangular strip packing problem (2D-SPP), where the main goal is to pack a given number of rectangles without any overlap to minimize the height of the strip. Real-life constraints must be considered when developing 2D-SPP algorithms to deliver solutions that will improve the cutting processes. In the 2D-SPP literature, a gap related to studies approaching constraints in real-life scenarios was identified. Therefore, the impact of real-life constraints found in the plasma cutting process in sheet metal waste was analyzed. A mathematical model from the literature was modified to obtain packing arrangements with plasma cutting constraints. The combination of size and number of rectangles, as well as strip width, was the main factor that affected the packing arrangement, limiting the allocation of rectangles and generating empty spaces. In summary, considering the sheet metal waste context, instances with smaller widths should be avoided in practical operations for high minimum distance constraint values, returning the worst packing arrangements. For low minimum distance constraint values, smaller width instances can be used in practical operations, as the packing arrangement is acceptable. Finally, this article can reduce material waste and enhance the cutting process in the sheet metal industry, by showing packing characteristics which lead to higher amounts of raw material waste.

The relationship between chemical structure of perfluorinated sulfonic acid ionomers and their membrane properties for PEMEC application

Polymer electrolyte membrane electrolyzer cells (PEMECs) has been confirmed as a prototype electrochemical system that is effective in converting water into hydrogen and oxygen under the application of electricity. Among the core components of PEMEC, the polymer electrolyte membrane (PEM) determines critically an overall electrochemical performance of the PEMEC. Ideally a PEM system should exhibit a complex transport behavior of small molecules (e.g., gases and ions) while mediating flows of ions in the cell; it should exhibit high proton selectivity while serving as a gas barrier to hydrogen and oxygen to increase current efficiency, which are in turn vital factors in determining an effectiveness when the electric energy is used for water electrolysis. Until now, perfluorinated sulfonic acid (PFSA) ionomers have been extensively used as PEM materials in water electrolysis while in generating hydrogen and oxygen gases simultaneously in high purity. In this study we have examined the chemical structure of PEM membranes derived from various types of PFSA ionomers by employing solid-state 19F MAS NMR. Subsequently, a structure-property-performance correlation was sought in accordance with the chemical structure, the dispersion characteristics, and membrane properties of PFSA ionomers. Furthermore, the effects of the membrane morphology as well as the ionomer packing characteristics on proton conduction and hydrogen transportation were investigated. Lastly, the membrane properties exerted by varying the chemical architectures and equivalent weight (EW) values of PFSA ionomers in PEMEC were confirmed. 3 M 725 membrane, which has the highest concentration of sulfonic acid groups in the hydrated state, has the highest proton conductivity. In addition, it showed the best water electrolytic cell performance via the synergistic effect with low gas permeability obtained as a result from the short side chain structure.

Statistical mix design method for self-compacting concrete with limestone fillers

This study presents a statistical mix design method for self-compacting concrete (SCC) with limestone fillers (LF) content that considers mortar rheological properties and material packing characteristics. The effect of LF on the rheological properties of SCC was investigated through seven SCC mixes with different LF replacement levels. A basic water demand experiment was designed to obtain the packing density of mortar, and the equivalent packing density was defined and calibrated to represent the effect of LF. The relative spread and relative flow formula were modified based on the equivalent packing density, and the bilinear interpolation method was used to analyses the mortar results.

Will laboratory and pilot plant columns soon become superfluous? – A concept for the determination of structured packing characteristics in a measuring cell under distillation conditions

A new approach to carry out separation performance tests for structured packings is introduced through a newly designed measuring cell. To characterize this measuring cell, a suitable test system was identified and measurements regarding the separation performance as well as the dry and wet pressure drop were conducted. Furthermore, experiments were carried out with similar boundary conditions in columns of varying diameters (DN 50, DN 80, DN 250). The paper presents a comparison of the results gained to demonstrate the transferability and information value of the new measuring cell in comparison to conventional lab and pilot-plant columns. To our knowledge, these are the first investigations evaluating the separation performance of distillation processes in small measuring cells of this kind.

Weak Interaction Based Interpretation of Crystal Packing Characteristics of Aromatic Rings Accumulating Molecules: Hirshfeld Surface Analyses Reinforced X-ray Crystal Study on 1,8-Dibenzoyl-7-Ethoxynaphthalen-2-ol and Its 2-Ethoxylated Homologue

Weak Interaction Based Interpretation of Crystal Packing Characteristics of Aromatic Rings Accumulating Molecules: Hirshfeld Surface Analyses Reinforced X-ray Crystal Study on 1,8-Dibenzoyl-7-Ethoxynaphthalen-2-ol and Its 2-Ethoxylated Homologue