Mesostructure Properties Research Articles

Characterization on the mesostructural properties of asphalt mixtures based on meso-element equivalence method

The randomness and variation of material composition at the meso-scale lead to some limitations in the application of asphalt mixture. When all features are taken into account, the computational effort increases significantly. Therefore, the relationship can be established using the meso-element equivalence method (MEEM). In this paper, the effects of aggregate-asphalt interface, initial void defects and material damage were introduced and MEEM of asphalt mixture was established based on industrial computed tomography (ICT) and finite element method (FEM). The rationality of the model was verified by laboratory performance tests, and the effects of aggregate type, mixture gradation and mesostructural parameters on the mechanical response of MEEM were compared and analyzed. The results showed that the MEEM model captures the mechanical behavior of asphalt mixtures well, the input of visco-elastic material parameters is an important step of MEEM simulation accuracy. The aggregate type, the discrete degree of the skeleton structure and the distribution characteristics of mesostructural parameters are important factors affecting the mechanical properties of asphalt mixture in MEEM.

Predicting the hyperelastic properties of alginate-gelatin hydrogels and 3D bioprinted mesostructures

Additive manufacturing has been widely used in tissue engineering, as 3D bioprinting enables fabricating geometrically complicated replacements for different tissues and organs. It is vital that the replacement mimics the specific properties of native tissue and bears the mechanical loading under its physiological conditions. Computational simulations can help predict and tune the mechanical properties of the printed construct—even before fabrication. In this study, we use the finite element (FE) method to predict the mechanical properties of different hydrogel mesostructures fabricated through various print patterns and validate our results through corresponding experiments. We first quantify the mechanical properties of alginate-gelatin hydrogels used as matrix material through an inverse approach using an FE model and cyclic compression-tension experimental data. Our results show that the fabrication process can significantly affect the material properties so that particular caution needs to be paid when calibrating FE models. We validate our optimized FE model using experimental data and show that it can predict the mechanical properties of different mesostructures, especially under compressive loading. The validated model enables us to tune the mechanical properties of different printed structures before their actual fabrication. The presented methodology can be analogously extended for cell bioprinting applications, other materials, and loading conditions. It can help save time, material, and cost for biofabrication applications in the future.

Repartitioning-based aggregate generation method for fast modeling 3D mesostructure of asphalt concrete

A repartitioning-based aggregate generation method is proposed to establish the three-dimensional mesostructure models of asphalt mixture. In this method, a stepwise partitioning procedure is proposed to repeatedly partition the specimen space into Voronoi cells with high variation in shape and size. The number of the Voronoi cells is determined by dividing the volume of the specimen space by the volume of a so-called equivalent sphere; in this way, the sizes of the generated Voronoi cells can be controlled around the sizes of the equivalent spheres. Also, a reshaping-classifying-picking procedure is developed and applied to the Voronoi cells to obtain very realistic aggregates with expected gradations to form final mesostructures. The effectiveness of the repartitioning-based aggregate generation method was validated by using the aggregate gradation and complex modulus test data of asphalt concrete. Compared with several recent aggregate generation methods, the proposed method can faster generate three-dimensional mesostructures with large dimension and high aggregate content. Besides, it can explain quantitatively the effects of mesostructural properties on macromechanical characteristics of asphalt concrete, thus providing an efficient and robust tool for advancing material design of asphalt concrete.

Peridynamic modeling for impact failure of wet concrete considering the influence of saturation

In this paper, a modified intermediately homogenized peridynamic (IH-PD) model for analyzing impact failure of wet concrete has been presented under the configuration of ordinary state-based peridynamic theory. The meso-structural properties of concrete are linked to the macroscopic mechanical behavior in the IH-PD model, where the heterogeneity of concrete is taken into account, and the calculation cost does not increase. Simultaneously, the porosity of concrete is considered, which is implemented by deleting the bond between two material points, as well as the influence of porosity on the mechanical properties of concrete. Moreover, the effective bulk and shear modulus of cement mortar in wet concrete (saturated and unsaturated concrete) are calculated respectively. The dynamic model for wet concrete is described from three aspects: strength, dynamic increase factor, and equation of state. Validation of the proposed model is established through analyzing some benchmark tests and comparing with the corresponding experiment and other available numerical results.

Post-harvest maturation of Hevea brasiliensis latex coagula: ranking of the key drivers of the mesostructure and physical properties of natural rubber

Post-harvest maturation of Hevea brasiliensis latex coagula: ranking of the key drivers of the mesostructure and physical properties of natural rubber

Multiscale, Nano‐ to Mesostructural Engineering of Silk Biopolymer‐Interlayer Biosensors for Continuous Comonitoring of Nutrients in Food

AbstractNutrition measurement has broad applications in science, ranging from dietary assessment, to food monitoring, personalized health, and more. Despite its importance, there are currently no tools that offer continuous cotracking of nutrients direct from food. In this study, the multiscale engineering of silk biopolymer‐interlayer sensors is reported for comonitoring of nutrients. By manipulating various nano‐ to mesostructural properties of such biosensors, sensors are obtained with programmable sensitivity and selectivity to salts, sugars, and oils/fats. Notably, this approach requires no specialized nanomaterials or delicate biomolecules. Programmable biosensors are further formatted for wireless readout and characteristics of these passive, wireless nutrient monitors are studied in vitro. As a proof of concept, the discrimination and comonitoring of salt, sugar, and fat content direct from real, complex foods such as milk, meat, soup, and tea drinks are demonstrated. It is anticipated that such sensors can be utilized in emerging dietary tools for applications across food tracking and human health. In addition, such strategies are expected in structural engineering of sensors to be adaptable to existing or emerging selective or partially selective sensors.

A multiscale analysis approach to predict mechanical properties in fused deposition modeling parts

Additive manufacturing has evolved from a rapid prototyping tool to a set of manufacturing processes for functional parts. One of their most outstanding features is the ability to build complex geometry parts. However, their industrial application is limited because these parts exhibit heterogeneous and porous micro/mesostructures with anisotropic behavior. These structural characteristics, mainly porosity, are strongly related to the building parameters. In this work, a computational multiscale homogenization approach was implemented to determine the mechanical properties of unidirectional and criss-cross mesostructures generated by a material extrusion process (MEP). Representative volume elements (RVE) for simplified and real-like pore geometries were created to model the mesostructures and to perform the multiscale analysis. Stiffness tensor for each RVE was obtained and graphically represented to observe the mechanical properties as a function of the orientation. A great influence of the pore geometry on mechanical properties was observed. Finally, by comparing with experimental data, the results obtained were validated.

Chiral Mesoporous Silica Materials: A Review on Synthetic Strategies and Applications.

Because of its tunable textural properties and chirality feature, chiral mesoporous silica (CMS) gained significant consideration in many fields and has been developed rapidly in recent years. In this review, we provide an overview of synthesis strategies for fabricating CMS together with its main applications. The properties of CMS, including morphology and mesostructures and enantiomer excess (ee), can be altered according to the synthetic conditions during the synthesis process. Despite its primary stage, CMS has attracted extensive attention in many fields. In particular, CMS nanoparticles are widely used for enantioselective resolution and adsorption of chiral compounds with desirable separation capability. Also, CMS acts as a promising candidate for the effective delivery of chiral or achiral drugs to produce a chiral-responsive manner. Moreover, CMS also plays an important role in chromatographic separations and asymmetric catalysis. There has been an in-depth review of the synthetic methods and mechanisms of CMS. And this review aims to give a deep insight into the synthesis and application of CMS, especially in recent years, and highlights the significance that it may have in the future.

Synthesis of Ordered Mesoporous Zr-Al Composite Oxides with Excellent Structural and Textural Properties and Extremely High Stability.

Ordered mesoporous Zr-Al composite oxide materials (denoted as OMZA-x) with different Zr contents have been synthesized by a solvent evaporation-inducing self-assembly procedure associated with a thermal treatment at 100 °C. A cooperative co-assembly process of amphiphilic triblock copolymer F127 molecules and inorganic hydroxyl species originated from the hydrolysis of Zr and Al precursors was proposed to explain the synthesis of OMZA-x. Compared to ordered mesoporous alumina prepared without introducing Zr species, the resultant OMZA-x exhibited a much more ordered mesostructure combined with a distinct increase in the pore volume and specific surface area. The highly homogenous doping of Zr into the mesopore walls together with the formation of Zr-O-Al bonds can effectively enhance the thermal and hydrothermal stability of OMZA-x. For instance, the ordered mesostructure and excellent textural properties of OMZA-6 prepared with the optimum atomic ratio of Al to Zr of 6 could be well maintained even after a high-temperature treatment at 1000 °C for 1 h or a hydrothermal treatment at 100 °C for 6 h.

Improvement of visible-near-infrared (NIR) broad spectral photocurrent application of PbSe mesostructures using tuning the morphology and optical properties

PbSe mesostructures were synthesized for the broad spectral photocurrent applications from visible region till NIR region. The morphology and optical properties of PbSe mesostructures, which were synthesized by a co-precipitation method, were tuned by different Se/Pb ratios. X-ray diffraction patterns (XRD) and Raman spectra of all seven samples with Se/Pb = 0.7–1.3 ratios indicated that, the samples had the same phase and structure. Scanning electron microscope (SEM) images showed the morphology of the most samples was cubic that the size of these cubics was changed by different Se/Pb ratio. Ultraviolet-visible-nearinfrared (UV–vis-NIR) spectroscopy results of the samples showed that, PbSe mesostructures were able to absorb visible-NIR broad spectra. According to the optical properties, the samples were used to fabricate the photoresponse devices that worked in the broad spectral from the visible to NIR regions. The samples with Se/Pb < 1 showed higher photocurrent intensity and faster response. Mott-Schottky results showed that, all samples were n-type semiconductors and donor carriers concentration is higher for the samples with Se/Pb < 1 ratio. In addition, this result indicated more positive value for flat band potential (Vfb) of the samples with Se/Pb < 1 ratio. X-ray photoelectron spectroscopy (XPS) results also revealed more positive value for the conduction band energy (ECB) of the sample with Se/Pb < 1 ratio. The obtained results showed that, more positive Vfb and ECB of the samples with Se/Pb < 1, as well as higher donor concentration of these samples were three important factors to obtain a photodetector device with higher photocurrent and faster photoresponse.

Investigation of structure–mechanical property relationship in fused filament fabrication of the polymer composites

Fused filament fabrication (FFF) process is an emerging 3D printing technique primarily used for rapid prototyping in academic and industrial environments. The mechanical properties of these 3D-printed samples are highly anisotropic in nature and depend on various process parameters. Literature suggests that build orientation is a crucial parameter affecting the mesostructural and mechanical properties of these parts. However, there are no existing models that can correlate the mechanical properties of these printed parts with their mesostructural properties. Herein, a multiparametric mathematical model has been developed, establishing a correlation between the tensile strength, neck length, and pore size of the printed parts. An extensive investigation is carried out on six materials, namely acrylonitrile butadiene styrene (ABSplus P430, ABS POLYLAC® PA-757, and LG ABS RS657), polycarbonate (PC), FDM Nylon 12, and PC-ABS alloys printed in two different build orientations (XZ and ZX). The change in mechanical properties with respect to build orientation and the mesostructural properties was examined. It was established that parts printed in the XZ orientation exhibit a higher tensile strength, owing to the higher neck length and smaller pore size. Regression analysis was carried out to develop mathematical models correlating the tensile strength with the mesostructural properties of the printed parts. A good agreement is observed between the theoretically predicted and experimentally found tensile strength.

Cyclodextrin Functionalized Mesoporous Silica for Environmental Remediation of Methylene Blue Dye.

Functionalization of mesoporous silica KIT-6 with β-cyclodextrin (β-CD) was successfully realized via post-grafting method as a new adsorbent for environmental remediation of methylene blue (MB) dye from aqueous solutions. The mesostructure properties were characterized by transmission electron microscope (TEM), low-angel X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) and N₂ sorption isotherm. The remarkable adsorption of MB into β-CD-KIT-6 adsorbent was studied using UV-visible spectroscopy. The β-CD-KIT-6 exhibited higher adsorption capacity compared with unmodified-KIT-6. The adsorption behavior of MB into the β-CD-KIT-6 and unmodified-KIT-6 was carefully investigated using different kinetic and isotherm models. The adsorption process followed a pseudo-second order kinetic model and well-fitted to Langmuir isotherm. The thermodynamic parameters were evaluated and the adsorption of MB was found to be an exothermic and spontaneous process. The adsorption of MB into the β-CD-KIT-6 was highly dependent on the solution pH.

PH-mediated control over the mesostructure of ordered mesoporous materials templated by polyion complex micelles.

Ordered mesoporous silica materials were prepared under different pH conditions by using a silicon alkoxide as a silica source and polyion complex (PIC) micelles as the structure-directing agents. PIC micelles were formed by complexation between a weak polyacid-containing double-hydrophilic block copolymer, poly(ethylene oxide)-b-poly(acrylic acid) (PEO-b-PAA), and a weak polybase, oligochitosan-type polyamine. As both the micellization process and the rate of silica condensation are highly dependent on pH, the properties of silica mesostructures can be modulated by changing the pH of the reaction medium. Varying the materials synthesis pH from 4.5 to 7.9 led to 2D-hexagonal, wormlike or lamellar mesostructures, with a varying degree of order. The chemical composition of the as-synthesized hybrid organic/inorganic materials was also found to vary with pH. The structure variations were discussed based on the extent of electrostatic complexing bonds between acrylate and amino functions and on the silica condensation rate as a function of pH.

PH responsive selective protein adsorption by carboxylic acid functionalized large pore mesoporous silica nanoparticles SBA-1

Cubic mesoporous silica nanoparticles (MSNs) with the SBA-1 moiety, functionalized with carboxylic acid (COOH) groups as well as enlarged mesopores, are successfully synthesized using tetraethyl orthosilicate (TEOS) and carboxyethylsilanetriol sodium salt (CES) as silica sources, complexes formed by polyacrylic acid (PAA) and hexadecylpyridinium chloride (CPC) as templates, and trimethylbenzene (TMB) as pore expander. The successful incorporation of organic functionalities are confirmed by 13C and 29Si solid-state NMR. The structural properties of cubic mesostructures are characterized by powder XRD, N2 adsorption-desorption isotherms, and TEM measurements. The prepared MSNs exhibit a remarkably high adsorption capacity of 1138 mg g−1 at pH 8.2 when they are used as the supports to immobilize papain. Both factors of the large pore size of the support and the favorable electrostatic attractions between the carboxylate groups on the adsorbent surface and the papain molecules play important roles in reaching such a high adsorption capacity. The immobilized papain possesses better thermal stability, pH tolerance, and heat resistance in comparison to the free papain. The materials are also used for selective adsorption of a single protein (papain) from the binary mixture of two different types of proteins (papain and hemoglobin). Our results demonstrate that proteins such as papain and hemoglobin with different isoelectric points and shapes can be effectively separated from their binary mixture by simply tuning the pH of the buffer.

Influence of pore size and surface area of mesoporous silica materilas (MCM-41 and KIT-6) on the drug loading and release

Mesoporous silica KIT-6 and MCM-41 with different pore sizes has been prepared through the sol–gel and hydrothermal method, respectively. The synthesized mesoporous materials were modified by a chemical modification using 3-aminopropyl triethoxysilane (APTES) to obtain KIT-6-NH2 and MCM-41-NH2 as drug delivery carriers. The mesostructure properties was fully characterized by scanning electron microscope (SEM), N2 sorption isotherm, Fourier transform infrared (FT-IR), X-ray diffraction (XRD). Loading of resveratrol (RSV) drug as a model into synthesized mesoporous carriers and amine functionalized forms were studied using thermogravimetric analysis (TGA) and UV–visible spectroscopy (UV–Vis). The loading uptake and release behavior of RSV was highly dependent on the textural properties (such as pore size and surface area) of mesoporous silica and modified carriers. The release of drugs was carefully studied in different pH. The effect of the synthesized carriers and RSV@mesoporous drug carriers on MCF-7 human breast cancer cell line viability was evaluated. Both carriers alone revealed no toxicity to MCF-7 cancer cells. But, RSV@carriers or RSV@modified carriers indicated an inhibition of cell livability, when compared to the non-encapsulated drug. RSV@modified mesoporous carriers demonstrated cell viability inhibition better than RSV@mesoporous carriers. The inhibition of cell viability of RSV@modified mesoporous carriers depends on surface area and functionalized groups of carriers more than pore size. First order, Higuchi, HixsoneCrowell and KorsmeyerePeppas release kinetic models were applied to the experimental data and the release was found to obey a first-order rate kinetic.

Amine-functionalized mesoporous silica KIT-6 as a controlled release drug delivery carrier

Mesoporous silica KIT-6, has been prepared through the sol-gel method followed by a chemical modification using 3-aminopropyl triethoxysilane (APTS) to obtain KIT-6-NH2 as a drug delivery carrier. The mesostructure properties was fully characterized by transmission electron microscope (TEM), N2 sorption isotherm, Fourier transform infrared (FT-IR), low-angel X-ray diffraction (XRD) and small-angel x-ray scattering (SAXS). Loading of ketoprofen (KP) and 5-flurouracil (5-FU) drugs as models into KIT-6 and KIT-6-NH2 was studied using quartz crystal microbalance (QCM) and UV–visible spectroscopy. The loading uptake and release behaviors of KP and 5-FU were highly dependent on the textural properties of KIT-6 and KIT-6-NH2. The release of drugs was carefully studied in simulated gastric fluid (pH 2) and in simulated intestinal fluid (pH 7.4). First order, Higuchi, Hixson–Crowell and Korsmeyer–Peppas release kinetic models were applied to the experimental data and the release was found to obey a first-order rate kinetic.

Electrochemistry in the Next Generation of Rechargeable Batteries: Challenging the Maze with Multiscale Computational Modeling

The development of the next generation of rechargeable batteries and their consequent market penetration, require a rational guide for the optimization of the balance between the intrinsic capacity of the used storage materials, their statistical utilization in the composite electrodes and the macroscopic cell design. Computational multiscale modeling emerges nowadays as a powerful tool for building such a rational guide through the in silico representation of complex processes involving electrochemistry and species transport in operando conditions [1-3]. In this contribution we discuss our most recent progresses on the development of a novel integrative multiscale modeling platform devoted to understand the impact of the electrodes mesostructure on the electrochemical response of rechargeable batteries. The platform is supported on a combination of deterministic (continuum) and stochastic (Kinetic Monte Carlo) models resolving detailed electrochemistry and reactants/charge transport [4-6]. It allows capturing, with three-dimensional resolution, the impact of properties such as active material particles percolation, pore size distributions and pores interconnectivity, on the discharge cell performance (Figure). The flexibility of the approach is illustrated here through the investigation of hierarchical carbons as positive host electrode material in lithium-sulfur [7] and lithium-O2 batteries. In general, simulations reveal heterogeneities on the spatial location of electrochemical activity and nucleation centers with a strong dependence on the carbon mesostructural properties. Specific similarities and differencies between the two illustrated applications are discussed and possible ways for optimizing the electrodes performance are suggested. [1] Physical Multiscale Modeling and Numerical Simulation of Electrochemical Devices for Energy Conversion and Storage: From Theory to Engineering to Practice. A.A. Franco, M.L. Doublet, W.G. Bessler (Eds.), Springer (2015). [2] A.A. Franco, RSC Advances, 3 (32) (2013) 13027. [3] A.A. Franco (Ed.), Rechargeable Lithium Batteries: From Fundamentals to Applications, Woodhead/Elsevier Science (2015). [4] G. Blanquer, Y. Yin, M.A. Quiroga, A.A. Franco, J. Electrochem. Soc., 163 (3) (2016) A329. [5] K. H. Xue, E. McTurk, L. Johnson, P.G. Bruce, A.A. Franco, J. Electrochem. Soc., 162 (4) (2015) A614. [6] M. Quiroga, K.H. Xue, T.K. Nguyen, H. Huang, M. Tulodziecki, A.A. Franco, J. Electrochem. Soc., 161(8) (2014) E3302. [7] K.H. Xue, V. Thangavel, Y. Mammeri, M.A. Quiroga, C. Guery, P. Johansson, M. Morcrette, A.A. Franco, in preparation (2015). Figure 1

A facile approach to synthesize MCM-41 mesoporous materials from iron ore tailing: Influence of the synthesis conditions on the structural properties

In this paper, a facile synthesis route to obtain mesoporous MCM-41 silica using cetyltrimethyl ammonium bromide (CTAB) as template and iron ore tailing as raw material was reported. The effects of various synthesis conditions on the mesostructure properties of MCM-41, including the molar ratio of CTAB to SiO2, gelation pH, aging temperature, aging time and calcination temperature, were investigated in detail. Powder X-ray diffraction (XRD), N2 adsorption–desorption isotherms, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques had been employed to characterize the samples. The molar ratio of CTAB to SiO2 and the gelation pH play an important role in the synthesis of ordered MCM-41 mesoporous material structure. The synthesized MCM-41 mesoporous material possessed a BET surface area of 882m2/g, a pore size of 4.2nm and a pore volume of 1.019cm3/g in the condition of CTAB to SiO2 in a molar ratio of 0.10:1, pH of 10, crystallization temperature of 100°C, crystallization time of 48h and calcination at 550°C for 3h. All the results demonstrated the feasibility of employing iron ore tailing as silicon source to produce MCM-41 and provided a new way to convert a solid waste to a value-added material, which has the potential application in the large-scale production of MCM-41.

Some considerations regarding the mesopore structure and order in MSU-3 and MSU-F (organo)silicas

Development of mesoporous materials and specifically mesoporous silica was an advancement of that of microporous materials such as zeolites. Major advantages associated with mesopore nanostructures have largely depended on bigger pore size, high pore order and rather high flexibility in modification of the pore system. For this reason, large-pore and highly ordered mesoporous silica (e.g. SBA-15) were introduced taking advantage of co-polymer surfactants as structure directing agents, while pore size expansion was still extended toward making mesoporous silica foams. At the same time neutral cooperative self-assembly of silica precursors and non-ionic surfactants resulted in facile preparation of MSU-X family of mesoporous silica obtained in milder synthesis conditions. This research tries to bring new insights into the versatility of MSU-X preparations that would show highly ordered or engineered mesopore network. The mesostructural properties of MSU-3 and MSU-F materials subjected to hydrothermal processing and different functionalization were studied in detail with gas adsorption, TEM and XRD analyses. Use of different silica precursors and functionalizations brought differences in the mesopore structure. It was possible, in these syntheses, to obtain highly hexagonal mesopore order in the hybrid MSU-3 in a co-condensation synthesis with MPTMS in presence of inorganic silica precursor. On the other hand, during the course of silica foam (MSU-F) preparations, due to the effect of post-synthesis hydrothermal processing, considerable modification of the large mesopores brought the opportunity to achieve fully bimodal (both channel-like and mesocellular) pore morphologies in the material framework.

Facile route to synthesize mesoporous silica SBA-15 platelets

Highly ordered mesoporous silica SBA-15 platelets have been directly synthesized using triblock copolymer P123 as structure-directing agent and tetraethyl orthosilicate (TEOS) as silica source without additives. By tuning the synthesis temperature and HCl concentration, platelet-like SBA-15 particles with short pore (150–350 nm) running parallel to the thickness of platelets could be facilely obtained. The synthesis temperature and acidity revealed strong effect not only on mesostructural properties, but also on macrostructural morphologies of the obtained materials. It was found that the side to side aggregation of primary particles in an oriented manner occurred and platelet-like particles were formed at the appropriate temperature and acidity. Furthermore, possible mechanism for the growth of SBA-15 platelets was suggested.