Internal Pore Structure Research Articles

Polyvinyl alcohol gel/micro-arc oxidation 3D-printed porous structural aluminium for oil-water separation

Traditional oil-water separation membranes still face challenges in designing membrane structures and pore sizes. In this study, we successfully prepared a PVA@MAO 3D-Al material with an internal porous structure using 3D printing technology and micro-arc oxidation (MAO). Compared to the base 3D-Al material, the fabricated PVA@MAO 3D-Al exhibits excellent wear resistance, with an average friction coefficient reduced by 66 % in dry friction and 22 % in water lubrication. In electrochemical experiments, corrosion current density decreased by an order of magnitude, indicating higher stability of PVA@MAO 3D-Al in corrosive environments. In oil-water separation experiments, PVA@MAO 3D-Al achieved separation efficiencies exceeding 97 % for mixtures of white oil, kerosene, liquid paraffin, and cyclohexane with water. Moreover, even after undergoing 600 cycles of reciprocating friction and exposure to various environmental solutions, the separation efficiency of PVA@MAO 3D-Al for white oil/water mixtures remained above 96 %, demonstrating outstanding physical and chemical stability. This suggests that PVA@MAO 3D-Al is suitable for use in extremely harsh environments. This study introduces a simple and efficient approach to manufacturing oil-water separation membranes using 3D printing technology, coupled with MAO technology to enhance the base material's performance. The combination of these techniques opens up new avenues in the field of oil-water separation.

In-situ CT study on the effect of cyclic gas injection and depletion exploitation on the phase behavior of fractured condensate gas reservoirs

Using subterranean rock cores as samples, the impact of depletion exploitation and cyclic gas injection on the occurrence and dynamic utilization of condensate oil and the damage to reservoirs were studied. Initially, the internal pore structure of the rock core was analysed using computer tomography (CT), followed by depletion and cyclic gas injection experiments, with in-situ CT scanning of the samples. The results indicate that under different fracture apertures, condensate oil exhibits wave flow and slug flow states. The production effectiveness of cyclic gas injection is significantly superior to depletion exploitation production, with condensate oil saturation decreasing by over 30%. During cyclic gas injection, fractures serve as the main flow channels, with condensate oil being extracted first. In cyclic gas injection, the most significant effect is seen during the first injection, with a decrease in oil saturation of around 3%. Subsequent injections show decreases of approximately 1% and 0.5% in oil saturation respectively. As the gas injection volume increases, the extent of cumulative production rate improvement also gradually increases; however, once the injection volume reaches the reservoir pressure, the rate of cumulative production rate improvement will gradually decrease. These findings provide technical support for optimizing the development mode of condensate gas reservoirs, clarifying the seepage law of condensate oil and gas, and providing technical support for the efficient development of fractured condensate gas reservoirs.

Properties of Fiber-Reinforced Geopolymer Mortar Using Coal Gangue and Aeolian Sand.

Geopolymers, as a novel cementitious material, exhibit typical brittle failure characteristics under stress. To mitigate this brittleness, fibers can be incorporated to enhance toughness. This study investigates the effects of varying polypropylene fiber (PPF) content and fiber length on the flowability, mechanical properties, and flexural toughness of coal gangue-based geopolymers. Microstructural changes and porosity variations within the Fiber-Reinforced Geopolymer Mortar(GMPF) matrix were observed using scanning electron microscope (SEM) and Low field NMR(LF-NMR) to elucidate the toughening mechanism of PPF-reinforced geopolymers. The introduction of fibers into the geopolymer matrix demonstrated an initial bridging effect in the viscous geopolymer slurry, with a 3.0 vol% fiber content reducing fluidity by 5.6%. Early mechanical properties of GMPF were enhanced with fiber addition; at 1.5 vol% fiber content and 15 mm length, the 3-day flexural and compressive strengths increased by 30.81% and 17.4%, respectively. Furthermore, polypropylene fibers significantly improved the matrix's flexural toughness, which showed an increasing trend with higher fiber content. At a 3.0 vol% fiber content, the flexural toughness index increased by 198.35%. The data indicated that a fiber length of 12 mm yielded the best toughening effect, with an 84.03% increase in the flexural toughness index. SEM observations revealed a strong interfacial bond between fibers and the matrix, with noticeable damage on the fiber surface due to frictional forces, and fiber pull-out being the predominant failure mode. Porosity testing results indicated that fiber incorporation substantially improved the internal pore structure of the matrix, reducing the median pore diameter of mesopores and converting mesopores to micropores. Additionally, the number of harmless and less harmful pores increased by 23.01%, while the number of more harmful pores decreased by 30.43%.

Fluid‐Driven Particle Migration and Its Impact on Hydraulic Transmissivity of Stressed Filled Fractures

AbstractThe accurate assessment of hydraulic transmissivity in rock fractures filled with particles is not only a scientific challenge but also a critical need for various industrial applications. However, the intricate dynamics of particle erosion and pore clogging that govern transmissivity evolution remain largely unexplored. In this study, we experimentally examine the fluid‐driven particle migration behavior in filled fractures and its consequent impact on fracture transmissivity under various hydraulic gradients, normal stresses, and fracture apertures. We find that escalating hydraulic gradients not only intensify particle erosion through amplified fluid drag forces and hydro‐mechanical coupling effects but also lead to an increase in the size of migrating particles, thereby augmenting pore clogging. The dynamics of erosion and clogging define four distinct migration phases within the filled fractures. Variations in normal stress and initial fracture aperture significantly alter the particle arrangement and the soil structure stability within the fractures, thereby modulating the progress of particle migration in response to hydraulic gradients. The pattern of particle migration in filled fractures dictates the development of the internal pore structure and normal deformation, ultimately affecting fracture transmissivity. We propose an empirical expression to encapsulate the comprehensive evolution of fracture transmissivity across different particle migration patterns. Our research advances the understanding of fluid‐driven particle migration within filled fractures and provides a practical tool for the precise determination of hydraulic properties of fractured rocks amidst complex geological settings.

Simulating Two-Phase Seepage in Undisturbed Soil Based on Lattice Boltzmann Method and X-ray Computed Tomography Images.

The two-phase seepage fluid (i.e., air and water) behaviors in undisturbed granite residual soil (U-GRS) have not been comprehensively studied due to a lack of accurate and representative models of its internal pore structure. By leveraging X-ray computed tomography (CT) along with the lattice Boltzmann method (LBM) enhanced by the Shan-Chen model, this study simulates the impact of internal pore characteristics of U-GRS on the water-gas two-phase seepage flow behaviors. Our findings reveal that the fluid demonstrates a preference for larger and straighter channels for seepage, and as seepage progresses, the volume fraction of the water/gas phases exhibits an initial increase/decrease trend, eventually stabilizing. The results show the dependence of two-phase seepage velocity on porosity, while the local seepage velocity is influenced by the distribution and complexity of the pore structure. This emphasizes the need to consider pore distribution and connectivity when studying two-phase flow in undisturbed soil. It is observed that the residual gas phase persists within the pore space, primarily localized at the pore margins and dead spaces. Furthermore, the study identifies that hydrophobic walls repel adjacent fluids, thereby accelerating fluid movement, whereas hydrophilic walls attract fluids, inducing a viscous effect that decelerates fluid flow. Consequently, the two-phase flow rate is found to increase with then-enhanced hydrophobicity. The apex of the water-phase volume fraction is observed under hydrophobic wall conditions, reaching up to 96.40%, with the residual gas-phase constituting 3.60%. The hydrophilic wall retains more residual gas-phase volume fraction than the neutral wall, followed by the hydrophobic wall. Conclusively, the investigations using X-ray CT and LBM demonstrate that the pore structure characteristics and the wettability of the pore walls significantly influence the two-phase seepage process.

Seepage characteristics and mechanism of double damage basalt fiber reinforced concrete under three-dimensional variable stress states

Concrete experiences a three-dimensional variable stress state during its service life. To explore the permeability evolution and mechanism under such conditions, a permeability test was conducted on double damage basalt fiber concrete subjected to loading and unloading of twice confining pressure. Pore structure and microstructure of specimens were analyzed before and after permeability test. The findings reveal that the reduction in permeability after primary cycle of confining pressure loading and unloading is significantly higher than that after secondary cycle, and residual deformation is also more pronounced after primary cycle. Both high temperature and salt freeze-thaw cycles induce initial damage to specimens, consequently altering internal pore structure and subsequently impacting initial permeability. Notably, initial permeability decreases in the case of 10th salt freeze-thaw cycles, while it increases under other conditions. The greater the initial extent of damage to the specimen, the higher the permeability damage coefficient and the permeability damage rate. As the confining pressure decreases, the attenuated permeability increases, with the permeability decay rate reaching a significant 88.53 %. Plastic deformation of pores during loading and unloading process cannot be fully reversed, leading to the development of macropores and mesopores into smaller pore sizes, resulting in a remarkable 87.17 % increase in the proportion of micropores. Microscopic observations reveal smaller pores within the matrix, shorter crack lengths, and narrower crack widths in the specimen. The application of confining pressure reduces permeability channels within specimens, ultimately causing a decline in permeability.

Modification of a Carboxymethyl Cellulose/Poly(vinyl alcohol) Hydrogel Film with Citric Acid and Glutaraldehyde Crosslink Agents to Enhance the Anti-Inflammatory Effectiveness of Triamcinolone Acetonide in Wound Healing.

Anti-inflammatory wound healing involves targeted drug delivery to the wound site using hydrogel materials to prolong drug effectiveness. In this work, hydrogel films were fabricated using carboxymethyl cellulose (CMC) and poly(vinyl alcohol) (PVA) crosslinked with citric acid (CA) and glutaraldehyde (GA) at different concentrations. The crosslinker densities were optimized with various CA (2-10% w/v) and GA (1-5% v/v) concentrations. The optimized crosslink densities in the hydrogel exhibited additional functional group peaks in the FT-IR spectra at 1740 cm-1 for the C=O stretching of the ester linkage in CA and at 1060 cm-1 for the C-O-C stretching of the ether group in GA. Significantly, the internal porous structures of hydrogel composite films improved density, swelling capacities, solubility percentage reduction, and decreased water retention capacities with optimized crosslinker densities. Therefore, these hydrogel composite films were utilized as drug carriers for controlled drug release within 24 h during medical treatment. Moreover, the hydrogel films demonstrated increased triamcinolone acetonide (TAA) absorption with higher crosslinker density, resulting in delayed drug release and improved TAA efficiency in anti-inflammatory activity. As a result, the modified hydrogel showed the capability of being an alternative material with enhanced anti-inflammatory efficiency with hydrogel films.

Granular polyacrylonitrile with internal 3D channels for gold recovery from thiosulfate solution

Gold recovery technology is an urgent challenge in the industrialisation of thiosulfate-based gold extraction. Current materials used for gold recovery suffer from a lack of wear resistance and small particle size, which makes it difficult to separate the material from thiosulfate solutions. In this study, a cysteamine-functionalised granular polyacrylonitrile (cys-PANG) material containing three-dimensional channels was designed and synthesised. The results indicate that cys-PANG, prepared using a solvent exchange method, has remarkable adsorption capacity for gold, smooth outer surface, well-developed internal pore structure, high wear resistance, and controllable size, making it suitable for gold recovery from thiosulfate pulp. The adsorption of gold in a thiosulfate solution by cys-PANG followed the Freundlich isotherm and pseudo-second-order kinetic adsorption models with minimal pH dependence. Cys-PANG also demonstrated the effective adsorption of gold in a Cu(II)–ethanediamine (en)–S2O32− solution, even in the presence of copper and en interference. Both experimental results and theoretical calculations revealed that the interaction between cys-PANG and gold in the thiosulfate solution is predominantly characterised by charge attraction and ligand exchange mechanisms. Adsorption tests of cys-PANG in actual thiosulfate pulp demonstrated exceptional gold recovery properties and minimal wear even after 14 days of continuous stirring. This study presents a promising alternative methodology for the recovery of gold from thiosulfate pulp.

New insights into the mechanical behavior and enhancement mechanism of micro-steel-fiber-reinforced recycled aggregate concrete through in-situ 4D CT analysis

Micro-steel-fiber-reinforced recycled aggregate concrete (MSFR-RAC), an innovative and environmentally friendly construction material, is gaining traction in civil engineering due to its superior performance and sustainability. This study utilized in-situ CT tests to investigate the strength and deformation variations in MSFR-RAC influenced by micro-steel fibers. Calculation models for the fiber influence factor (FIF) on peak stress, peak strain, and ultimate strain were proposed, and the optimal volume fraction threshold for steel fibers was determined. Using CT scanning and 3D reconstruction, the internal pore structure, crack evolution, and spatial distribution of steel fibers were analyzed. The interaction mechanism between steel fibers and the concrete matrix was established based on crack evolution patterns. The results demonstrate that steel fibers significantly enhance the microscopic structure and mechanical performance of MSFR-RAC. This study provides essential technical and theoretical support for the design and application of MSFR-RAC in construction.

Toward high-resolution 3D-printing of pharmaceutical implants – A holistic analysis of relevant material properties and process parameters

In this work, filament-based 3D-printing, the most widely used sub-category of material extrusion additive manufacturing (MEAM), is presented as a promising manufacturing platform for the production of subcutaneous implants. Print nozzle diameters as small as 100 µm were utilized demonstrating MEAM of advanced porous internal structures at the given cylindrical implant geometry of 2 mm × 40 mm. The bottlenecks related to high-resolution MEAM of subcutaneous implants are systematically analyzed and the print process is optimized accordingly. Custom synthesized biodegradable phase-separated poly(ether ester) multiblock copolymers exhibiting appropriate melt viscosity at comparatively low printing temperatures of 135 °C and 165 °C were utilized as 3D-printing feedstock. The print process was optimized to minimize thermomechanical polymer degradation by employing print speeds of 30 mm∙s−1 in combination with a nozzle diameter of 150 µm at layer heights of 110 µm. These results portray the basis for further development of subcutaneous implantable drug delivery systems where drug release profiles can be tailored through the adaption of the internal implant structure, which cannot be achieved using existing manufacturing techniques.

Study on the effect of rubber content on the frost resistance of steel fiber reinforced rubber concrete

In cold areas, the steel fiber reinforced rubber concrete (SFRRC) pavement is exposed to natural environment and experiences varying degrees of damage from freezing and thawing. This can have a serious impact on the normal usage and safe operation of the pavement structure. This research examines the impact of varying rubber concentrations on multiple variables, such as the rate of mass reduction, relative dynamic modulus of elasticity, compressive strength, and thickness of the damage layer (Hf) during freeze–thaw (F-T) durability testing conducted on SFRRC. Furthermore, an analysis is conducted to determine the degradation pattern exhibited by SFRRC. The internal structure evolution and pore structure characteristics of SFRRC were examined using scanning electron microscopy and mercury intrusion porosimetry techniques, which revealed the underlying damage mechanism in SFRRC during F-T cycles. The results suggest that the addition of an appropriate amount of rubber can effectively enhance the frost resistance of SFRRC in water. A gradual improvement in the frost resistance of SFRRC is observed when increasing the rubber content from 0 to 10%. The optimal frost resistance is observed in SFRRC with 10% rubber content. However, when the rubber content reaches 15%, SFRRC exhibits significant degradation and lower level of resistance to freezing compared to SFRRC without rubber. Microcracks form within SFRRC due to the freezing–thawing forces experienced during the experiment, resulting in the development of a damage layer that extends from the surface to the interior. The compressive strength of the damaged layer significantly decreases as Hf increases. The addition of appropriate rubber in SFRRC improves its pore structure, leading to an increased proportion of harmless or less harmful pores and a reduction in average pore size, thereby significantly enhancing its frost resistance.

Effect of pore-forming agent on degradation of phenol by iron tailings based porous ceramics

In order to realize the resource utilization of solid waste and the treatment of phenol wastewater in China, a new porous ceramic granules (PCG) with the function of degrading phenol wastewater was prepared by using titanium-containing blast furnace slag, iron tailings and fly ash as raw materials, which realized the sustainable development of "treating waste with waste". The effects of different pore forming agents on the structure, morphology, ionic state of PCG samples and the adsorption behavior of phenol in aqueous solution were investigated. The results show that the change of pore forming agent has no obvious change on the crystal structure. When carbon powder (CP) and starch (SH) are used as pore forming agents, the internal pore structure is relatively dense and less porous, and it is not easy to form liquid channels. When ammonia bicarbonate (NH) is used as pore-forming agents, the internal pore structure is very developed and has many three-dimensional pore structures. Under the conditions of PH 2, phenol concentration 10 mg/L and solid-liquid ratio 3 g/L, TOC removal rates of CP-PCG, SH-PCG and NH-PCG samples after 72 h adsorption reaction were 39.10 %, 14.00 % and 93.29 %, respectively. In addition, the surface functional groups, hydrogen bonds and π-π interactions of PCG samples may be involved in the adsorption of phenol. This work not only provides a low-cost, environmentally friendly and simple technology for phenol-containing wastewater treatment, but also provides a new idea for the effective use of solid waste resources.

Oleogel for improving the texture and flavor in rice cooking: Preparation from natural wax and rice bran oil and characterization

This study involved the preparation and characterization of oleogels from rice bran oil with different waxes and the potential application in improving the texture and flavor in rice cooking. The findings revealed a substantial improvement in rice texture with the addition of oleogel, particularly noteworthy at a 3% (w/w) incorporation of RBW (Rice Bran Wax). Under this condition, the hardness reached 15.75N, and stickiness measured 2.16N. The incorporation of 1–3% (w/w) oleogel significantly enhances the color vibrancy of rice during the cooking process, resulting in an increase in the L* value of the rice from 73.86 to 73.95-76.74. Sensory evaluation revealed higher scores for BW (Bee Wax) and RBW at 40.68 and 40.23 points, respectively. Microscopic structural analysis indicated that the incorporation of RBW oleogel led to rice samples with the smallest pores, contributing to a more refined internal pore structure in the grains. In the control rice, 7 aldehyde compounds were detected with a relative content of 43.44%. The addition of oleogel increased the number of aldehyde compounds to 9, with a relative content of 48.06%. This study expands the potential applications of oleogels in rice cooking, enriching flavor profiles and presenting opportunities for integration into the food industry.

Study of the Performance of Emulsified Asphalt Shotcrete in High-Altitude Permafrost Regions

To improve the performance of shotcrete in high-altitude and low-temperature environments, emulsified asphalt shotcrete (EASC), which can be used in negative-temperature environments, was prepared by using low-freezing-point emulsified asphalt, calcium aluminate cement, and sodium pyrophosphate as modified materials. The effect of emulsified asphalt on the performance of shotcrete was investigated through concrete spraying and indoor tests. Then, the modification mechanism of emulsified asphalt with respect to EASC was analyzed by combining scanning electron microscopy images and the pore structure characteristics of EASC. The results showed that in a negative-temperature environment, the incorporation of emulsified asphalt delayed the formation of the peak of the cement hydration exotherm, slowed the rate of the cement hydration exotherm, reduced the thermal perturbation of permafrost by EASC, increased the cohesion of the concrete, improved the bond strength between EASC and permafrost, and reduced the rate of rebound. The mechanical strength of the studied EASC decreased upon increasing the amount of emulsified asphalt in the admixture, and its resistance to cracking gradually improved. A content of less than 5% emulsified asphalt could improve the internal pore structure of EASC, thus improving its durability. Increasing the content of emulsified asphalt affected the hydration process of the cement, and the volume content of the capillary pores and macropores increased, which reduced the durability of the EASC.

Investigation of key morphological parameters of pores in different grades of asphalt mixture based on CT scanning technology

The internal pore structure of asphalt mixtures directly influences their permeability characteristics. Current research has not yet clarified the quantitative characterization of different types of meso-pore structures and their impact mechanisms on permeability characteristics. Therefore, this study, based on the acquisition of the internal pore structure of asphalt mixtures through CT non-destructive scanning technology, classifies pores according to their characteristics. It conducts a multi-dimensional and multi-scale qualitative and quantitative analysis of the meso-pore structures of asphalt mixtures in terms of pore distribution, equivalent radius of pore throats, inclination angle of pore throats, tortuosity of pore throats, and pore connectivity. The results indicate that the internal pore distributions of AC-16, SMA-16, OGFC-13, and OGFC-16 gradation asphalt mixtures are uniform, without noticeable segregation. The results of porosity obtained through non-destructive CT scanning technology demonstrate good consistency with those of macroscopic experiments. This demonstrates that analyzing CT images can accurately acquire pores and quantify pore characteristics. The number of pores in AC-16 gradation specimens is approximately 3–5 times that of other groups of gradation specimens, but the average volume of the pores is only 0.98 mm3. The average pore volume for SMA-16 gradation is 5.1 mm3, while for OGFC-13 and OGFC-16 gradation, the average pore volumes are 28.3 mm3 and 29.6 mm3, respectively. In SMA-16 grade specimens, the volume of open pores accounts for 95% of the total pore volume, despite the fact that open pores make up only 1% of the total number of pores. In the OGFC-13 and OGFC-16 graded asphalt mixtures, the volumes of interconnected pores account for 88.7% and 88.9% of the total pore volume, respectively. The number and volume proportion of pore throats decrease with the increase in pore throats angle, indicating that there are more pore throats with smaller angles, which are conducive to longitudinal drainage, and fewer pore throats with larger angles, which are conducive to lateral drainage. This suggests that the vertical permeability of samples formed by traditional Marshall compaction is usually greater than their horizontal permeability.

Multi-scale study on the mechanical properties of concrete based on crack propagation under hygrothermal coupling

During the long-term service of structures, the environmental temperature and humidity fields can lead to the evolution of the pore structure within concrete materials, thereby affecting changes in mechanical properties. However, the mechanisms of their influence still need further clarification and are challenging to correlate for prediction. Addressing this specific issue, the current study focuses on evaluating 78 cubic concrete specimens with C30 and C40 strength grades. These specimens were subjected to a 95 % humidity environment at temperatures of 40 °C, 60 °C, and 80 °C for durations of 30, 60, and 90 days. The research involved conducting both microstructural and macroscopic mechanical tests to quantify the evolution of internal hydrates, pore structures, and pore distribution, as well as to assess the changes in the macroscopic mechanical properties of the specimens. To accurately predict the process, a multiscale finite element model (FEM) based on the bilinear continuum cohesive damage model was established. This model quantifies the changes in mechanical properties of mesoscopic three-phase concrete due to microcrack evolution under hygrothermal coupling. To facilitate multiscale simulations between the Representative Volume Element (RVE) and macroscopic scale models, relevant subroutines were written using Umath, and parallel computing was employed to reduce the computational burden. For the macroscopic model in this study, a homogenized concrete cube model with dimensions identical to the experimental specimens was selected. The effectiveness of the parallel computational model was validated by comparing and analyzing the simulation results under uniaxial compression with the experimental data. The findings indicate that hygrothermal action leads to the initiation and expansion of microcracks within the concrete, thereby impacting the alteration of its mechanical properties. In addition, the parallel computing-based multiscale FEM can more accurately quantify the typical damage process of crack propagation while reducing the computational load and may provide relatively accurate predictions of the mechanical characteristics of concrete under the influence of hygrothermal coupling, ensuring effective modeling of macroscopic structural specimens in various temperature and humidity environments.

Construction of Hydrogels with Highly Salt-Resistant Honeycomb Porous Structures for Solar Desalination and Steam Generation.

Interfacial solar desalination is a method for desalinating seawater using solar energy, and the long-term use of this technology requires a stable evaporation rate and some ability to prevent salt crystallization. To address these issues, carbonized polydopamine-coated bentonite (C@PBT), poly(vinyl alcohol), and cellulose nanofibers were used to construct a three-dimensional oriented hydrogel evaporator with a multilayered honeycomb porous structure for long-term desalination. Carbon nanoparticles transferred between the layers of the bentonite, which increases the spacing of the layers and confers a more effective solar light trapping ability. The evaporation rate was 2.26 kg m-2 h-1 in 20 wt % NaCl solution, and no salt crystals were precipitated from the surface of the evaporator in 12 h of continuous operation. This phenomenon occurs due to the wide distribution of pore sizes and the large size of the pores within the evaporator, which create ample space for salt ions to move freely. Furthermore, after undergoing 300 cycles of compression, its internal pore structure remains intact, and the rate of evaporation remains stable. It ensures the evaporator stability during outdoor cycles. The research work provides an effective method to solve the salt accumulation problem and shows its great potential for application.

Fabrication of controlled porous and ultrafast dissolution porous microneedles by organic-solvent-free ice templating method

Porous Microneedles (PMNs) have been widely used in drug delivery and medical diagnosis owing to their abundant interconnected pores. However, the mechanical strength, the use of organic solvent, and drug loading capacity have long been challenging. Herein, a novel strategy of PMNs fabrication based on the Ice Templating Method is proposed that is suitable for insoluble, soluble, and nanosystem drug loading. The preparation process simplifies the traditional microneedle preparation process with a shorter preparation time. It endows the highly tunable porous morphology, enhanced mechanical strength, and rapid dissolution performance. Micro-CT three-dimensional reconstruction was used to better quantify the internal structures of PMNs, and we further established the equivalent pore network model to statistically analyze the internal pore structure parameters of PMNs. In particular, the mechanical strength is mainly negatively correlated with the surface porosity, while the dissolution velocity is mainly positively correlated with the permeability coefficient by the correlation heatmap. The poorly water-soluble Asiatic acid was encapsulated in PMNs in nanostructured lipid carriers, showing prominent hypertrophic scar healing trends. This work offers a quick and easy way of preparation that may be used to expand PMNs function and be introduced in industrial manufacturing development.

Study on the mechanical properties and microstructure of recycled concrete reinforced with basalt fibers and nano-silica in early low-temperature environments

Abstract The effects of basalt fibers (BF) and nano-silica (NS) on the mechanical properties and microstructure of recycled concrete (RC) in early low-temperature environments were investigated by placing the BF and NS modified RC specimens in the environments of −20, −10, 0, and 25°C for curing for 6 h, followed by standardized maintenance. The damage morphology and mechanical properties of modified RC were analyzed in such environments. The formulae for the compressive strength of RC, which was affected by BF and NS, were fitted using statistical product and service solutions, and a micromorphological analysis of the modified RC was conducted using scanning electron microscope. The mechanical properties of RC decreased owing to the influence of early low temperatures, among which 0°C caused the largest damage crack and the most serious effects. In the early low-temperature environments, the physical properties of RC generally increased and then decreased with the increase in BF dosage; however, increasing NS dosages improved its mechanical properties. The composite doping of BF and NS was more obvious than the single doping of BF or NS to enhance the performance of RC, and the internal pore structure was considerably improved. The preferred doping amounts were 3 kg m−3 of BF and 2% NS.

Surface-Area Enhanced Raman Spectroscopy of DNA in Porous Silica: A Quantitative and Reproducible Alternative to Plasmonic-Based SERS.

Despite the success of surface-enhanced Raman spectroscopy (SERS) for detecting DNA immobilized on plasmonic metal surfaces, its quantitative response is limited by the rapid falloff of enhancement with distance from the metal surface and variations in sensitivity that depend on orientation and proximity to plasmonic "hot spots". In this work, we assess an alternative approach for enhancing detection by immobilizing DNA on the interior surfaces of porous silica particles. These substrates provide over a 1000-fold greater surface area for detection compared to a planar support. The porous silica substrate is a purely dielectric material with randomly oriented internal surfaces, where scattering is independent of proximity and orientation of oligonucleotides relative to the silica surface. We characterize the quantitative response of Raman scattering from DNA in porous silica particles with sequences used in previous SERS investigations of DNA for comparison. The results show that Raman scattering of DNA in porous silica is independent of distance of nucleotides from the silica surface, allowing detection of longer DNA strands with constant sensitivity. The surface area enhancement within particles is reproducible (<4% particle-to-particle variation) owing to the uniform internal pore structure and surface chemistry of the silica support. DNA immobilization with a bis-thiosuccinimide linker provides a Raman-active internal standard for quantitative interpretation of Raman scattering results. Despite the high (30 mM) concentrations of immobilized DNA within porous silica particles, they can be used to measure nanomolar binding affinities of target molecules to DNA by equilibrating a very small number of particles with a sufficiently large volume of low-concentration solution of target molecules.