Non-metallic fractions (NMFs) from waste printed circuit boards (PCBs) are mostly composed of cured resin and fiber. In this study, NMF material from a PCB was ground into powder and added into ...matrix asphalt to produce PCB-NMF-modified asphalt. To improve the compatibility of PCB-NMF and asphalt, a compatibilizer consisting of tung oil and glycerol was also developed. The optimum compatibilizer content was determined to be 8% by weight of the PCB-NMF through a series of laboratory tests, including the softening point, penetration, ductility, and softening point difference (SPD). The micro-mechanism of NMF powder-modified asphalt was analyzed through Fourier transform infrared spectroscopy (FTIR) and a scanning electron microscope test (SEM). The performances of PCB-NMF-modified asphalt were evaluated by the dynamic shear rheology (DSR) test and the low-temperature bending beam rheometer (BBR) test. The optimum compatibilizer content was 8% by weight of the NMF powder and the optimum content of NMF powder was determined to be 30% by weight of the asphalt based on a comprehensive evaluation. The results show that PCB-NMF can significantly improve stiffness, rutting resistance, high-temperature stability, and temperature sensitivity of asphalt material at an appropriate content. The BBR tests revealed that PCB-NMF slightly weakened the cracking resistance of asphalt at low temperatures. The SEM test showed that the addition of a compatibilizer can increase the compatibility by making the NMF powder evenly dispersed. The FTIR test results implied that a chemical reaction may not have happened between PCB-NMF, compatibilizer, and the matrix asphalt. Overall, it is a promising and sustainable way to utilize PCB-NMF as a modifier for asphalt material and reduce electronic waste treatment at a low cost.
To promote the resource utilization of steel slag and improve the production process of steel slag in steelmaking plants, this research studied the characteristics of three different processed steel ...slags from four steelmaking plants. The physical and mechanical characteristics and volume stability of steel slags were analyzed through density, water absorption, and expansion tests. The main mineral phases, morphological characteristics, and thermal stability of the original steel slag and the steel slag after the expansion test are analyzed with X-ray diffractometer (XRD), scanning electron microscope (SEM), and thermogravimetric analysis (TG) tests. The results show that the composition of steel slag produced by different processes is similar. The main active substances of other processed steel slags are dicalcium silicate (C
S), tricalcium silicate (C
S), CaO, and MgO. After the expansion test, the main chemical products of steel slag are CaCO
, MgCO
, and calcium silicate hydrate (C-S-H). Noticeable mineral crystals appeared on the surface of the steel slag after the expansion test, presenting tetrahedral or cigar-like protrusions. The drum slag had the highest density and water stability. The drum slag had the lowest porosity and the densest microstructure surface, compared with steel slags that other methods produce. The thermal stability of steel slag treated by the hot splashing method was relatively higher than that of steel slag treated by the other two methods.
For the characteristics of a random distribution and a large number of buses in the power system, the authors introduce distributed compressed sensing to compress and reconstruct the power quality ...data. They built a distributed IEEE14 bus system in PSCAD. This model was used to analyse the correlation and sparsity of power quality data and to obtain the four types of data that should be used in the latter simulation, the power quality data used in this study are the voltage amplitude of each bus in a power system. To make the signal sparser, they constructed a distributed compressed sensing learning dictionary for power quality data. The simulation results show that the performance of the distributed compressed sensing learning dictionary constructed in this study is more suitable for power quality data. The application of distributed compressed sensing in a power system can ensure the accuracy of reconstructed data when the quantity of data is reduced by 1/3, which greatly reduces the system storage space. Additionally, the speed of reconstruction also increases by 3/5.
Clinical deployment of oligonucleotides requires delivery technologies that improve stability, target tissue accumulation and cellular internalization. Exosomes show potential as ideal delivery ...vehicles. However, an affordable generalizable system for efficient loading of oligonucleotides on exosomes remain lacking. Here, we identified an Exosomal Anchor DNA Aptamer (EAA) via SELEX against exosomes immobilized with our proprietary CP05 peptides. EAA shows high binding affinity to different exosomes and enables efficient loading of nucleic acid drugs on exosomes. Serum stability of thrombin inhibitor NU172 was prolonged by exosome-loading, resulting in increased blood flow after injury in vivo. Importantly, Duchenne Muscular Dystrophy PMO can be readily loaded on exosomes via EAA (EXO
EAA-PMO
). EXO
EAA-PMO
elicited significantly greater muscle cell uptake, tissue accumulation and dystrophin expression than PMO in vitro and in vivo. Systemic administration of EXO
EAA-PMO
elicited therapeutic levels of dystrophin restoration and functional improvements in
mdx
mice. Altogether, our study demonstrates that EAA enables efficient loading of different nucleic acid drugs on exosomes, thus providing an easy and generalizable strategy for loading nucleic acid therapeutics on exosomes.
Synopsis
This study identifies an exosome-binding DNA aptamer (Exosomal Anchor Aptamer—EAA) and demonstrates that EAA binds to exosomes of different origins effectively and enables efficient loading of different nucleic acid drugs on exosomes. This study provides an easy generalizable strategy for loading nucleic acid therapeutics on exosomes orthogonal to CD63-binding peptides, which are better suited for protein and peptide loading.
EAA showed high binding affinity to exosomes irrespective of origin.
EAA enabled loading of different nucleic acid drugs on exosomes, with thrombin DNA aptamer inhibitor NU172 loaded on exosomes extended the serum stability.
Duchenne Muscular Dystrophy (DMD) phosphorodiamidate morpholino oligomers (PMOs) were efficiently loaded on exosomes via EAA to form EXO
EAA-PMO
and systemic administration EXO
EAA-PMO
at low doses improved muscle function and pathologies in dystrophic mice.
This study identifies an exosome-binding DNA aptamer (Exosomal Anchor Aptamer - EAA) and demonstrates that EAA binds to exosomes of different origins effectively and enables efficient loading of different nucleic acid drugs on exosomes. This study provides an easy generalizable strategy for loading nucleic acid therapeutics on exosomes orthogonal to CD63-binding peptides, which are better suited for protein and peptide loading.
Abstract The particle size and morphology of crushed stones impact their macroscopic mechanical and physical properties, which has become a hot topic in the study of road and geotechnical ...engineering. However, some reported studies fail to control the particle morphology as the only independent variable. This paper presented a new method to print artificial aggregates based on 3D printing technology of particles. The applicability of the new method was verified with uniaxial compression and dynamic modulus tests of asphalt mixtures formed by the printing aggregates. Results showed that the printing aggregates earned similar physical properties to real coarse when sintered at 1400 °C with alumina ceramic powder and CuO: TiO 2 a 1:2 additive in mass. Besides, the gross volume density, compressive strength, and shrinkage of the printing aggregates show a similar trend of increasing and then decreasing with the increase of additives. The optimal mass percentage of additives was obtained to be 5%. Mechanical tests indicated that the mechanical indexes of the asphalt mixtures formed with the two types of coarse aggregates were similar, while the results of the specimens formed with artificial coarse aggregates showed less dispersion. The stability of test results was significantly improved for different asphalt mixture specimens prepared with 3D printed coarse aggregate. This provides a basic method for further research on the multi-scale properties of particle material.
Compaction is the most critical stage during pavement construction, but the real-time rheological behavior in the compaction process of hot mix asphalt has not received enough attention. Rheological ...properties directly reflect the of mixture performance, the intrinsic directly reflects the influencing factors of compaction, and the pavement compactness and service life. Therefore, it is important to interpret the rheological properties of the asphalt mixture during the compaction process. In this paper, the improved Nishihara model was used to study the viscoelastic-plastic properties of the hot mix asphalt in the compaction process. Firstly, the improved Nishihara model was briefly introduced. Subsequently, the stress and strain correlation curves are obtained by the MTS (Material Testing System) compaction test, and the strain-time curve is fitted to determine the model parameter values. Finally, the parameters are substituted into the constitutive equation to obtain the strain-time curve and compared it with the test curve. The results show that the improved Nishihara model effectively depicts the real time behavior of the asphalt mixture in the compaction progress. The viscos and plastic parameters present certain differences, which reflects that the gradation and temperature have certain influence on the compaction characteristics of the mixture.
Good anti-skid performance was the basis for road safety, and it was discovered that the texture abrasion of pavement in service can directly affect its anti-skid performance. To analyze the ...influence mechanism of abrasion on the surface texture and anti-skid performance of asphalt pavement, this research collected high-precision texture data of different types of asphalt pavements with different degrees of abrasion. The macro and micro texture evaluation indexes were obtained after data filtering and separation, and correlation analysis was conducted with anti-skid performance indexes. The results showed that: the mean profile depth MPD-1 of asphalt pavement could characterize the macro texture abrasion properties well, and the root mean square deviation Rq-2 could characterize the micro texture abrasion well. Simultaneously, it was discovered that the skid resistance attenuation rate was AC > SMA > OGFC, and the larger the nominal maximum size of the same gradation, the lower the attenuation rate. It also found that enhancing the nominal maximum size of the asphalt mixture can effectively increase the macro texture, which in turn improved the anti-skid performance. The attenuation pattern of the macro texture index MPD-1 was consistent with the skid resistance, while the micro texture index Rq-2 decreased quickly in the early stage and was remain in the later stage. The research verified the feasibility of characterizing the skid resistance of asphalt pavements by macro and micro texture.
Asphalt mixture was a granular material, and traditional mechanical testing methods were difficult to reveal the failure mechanism. To evaluate the micromechanical behavior of asphalt mixture in the ...failure process, the DEM (Discrete Element Method) model of the uniaxial compression test was established. The virtual aggregate particle database with real morphology properties was constructed, and the linear parallel bond model was used to simulate the adhesion of asphalt. In the DEM model of the asphalt mixture failure process, the movement of asphalt mortar and coarse aggregate was evaluated, and the Discrete Fracture Network (DFN) was proposed to represent the microcrack. Finally, the three-dimensional spherical coordinate histogram was used to analyze the evolution of magnitude and direction of the coarse aggregate skeleton contact force. It found that the movement of coarse aggregate was less than that of asphalt mortar in the process of the uniaxial compression test, and the coarse aggregate movement was affected by its particle size and location. The result also found that although the adhesive and cohesion failure could occur at the same time, the adhesive failure was less than cohesion failure in the early stage of the uniaxial compression test, and the aggregate with larger particle size could reduce the generation of adhesive failure. Compared with the magnitude of coarse aggregate skeleton contact force, the change of direction was the main reason for a decrease in stress when the asphalt mixture specimen exceeded the peak strength.
The voids in mineral aggregate (VMA) design parameter is one of the most important in the current Superpave mix design procedure that links hot-mix-asphalt (HMA) mix properties to field performance. ...The success of achieving the appropriate VMA at an early stage of the mix-design process not only significantly impacts the design time and effort but also can produce an economical and reasonable design with good field performance. Although several current mix and gradation design methods have provided some guidance on adjusting gradation to achieve target VMA, these approaches still have to rely on initial experimental results with some degree of trial and error, and provide no direct correlation between aggregate gradation and VMA. This paper presents an analysis of aggregate packing and discrete-element modeling (DEM) simulation to link the aggregate gradation property to the VMA of HMA. A new definition is proposed for characterizing traditional dense-graded aggregate gradations into three types: coarse-graded, medium-graded, and fine-graded. A gradation weighing factor, fv, defined as the percentage of voids change by volume caused by unit additional aggregate, is developed to theoretically evaluate the packing of an aggregate structure. A method of VMA estimation based on the generated fv values is thus provided. Eleven mix designs from different states are used for verifying the accuracy of the prediction. Most predictions are within 1% difference of the design VMA. Using one nominal maximum aggregate size (NMAS) of 12.5 mm as an example, this study provided a promising method for a fast and accurate VMA estimation. It can be used directly in the HMA mix design to reduce the design time and effort, and contribute to the estimation of the HMA mixture performance at an early stage of the design period.
Through a simple performance dynamic modulus test (SPT), standard rutting test, Hamburg rutting test, French rutting test and asphalt pavement analyzer rutting test, the rutting resistance of asphalt ...mixtures in the middle and lower courses of three semi-rigid base asphalt pavement of Beijing full-scale test track road in China was evaluated. The test results show that the rutting resistance of asphalt mixtures of the middle and lower courses can be greatly improved by using low-grade asphalt, especially 30# asphalt. The rutting resistance of SBS modified asphalt mixtures is also better. The SPT dynamic modulus test can indirectly characterize the rutting performance of the asphalt mixture. The rutting test results of a laser road detection vehicle and 3 m ruler show that the asphalt grade has a significant impact on the rutting performance of semi-rigid base asphalt pavement. Compared with 70# asphalt used in the middle and lower courses, the rutting resistance of the pavement structure can be improved by more than 20%. The result also show that the APA rutting test results can closely characterize the full-scale test track results, which is an optimal test method for evaluating the rutting performance of semi-rigid base asphalt pavement. The research results can provide a theoretical basis and reference for the rational design and rutting evaluation of semi-rigid base asphalt pavement.
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