Search Results (12)

Ca₃(BO₃)₂ microwave dielectric ceramics with space group R-3c (#167) were prepared by cold sintering, and their properties were systematically investigated. Phonon density of state diagrams for the Ca₃(BO₃)₂ lattice were obtained based on first-principles calculations to provide a more comprehensive understanding of the lattice vibrational properties of the material. Raman scattering and infrared reflectance spectroscopy were employed to investigate the lattice vibrational characteristics, identifying two types of vibrational modes: internal modes associated with the planar bending and symmetric stretching vibrations of the [BO₃] group, and external modes linked to the vibrations of the [CaO₆] octahedron. The intrinsic dielectric properties were determined by fitting the experimental data using a four-parameter semi-quantum model. The results demonstrate that the dielectric properties of Ca₃(BO₃)₂ ceramics are primarily influenced by the external vibrational modes. The sample under 800 MPa exhibits optimal dielectric performance, with a dielectric constant (ε_r) of 5.95, a quality factor (Q × f) of 11,836 GHz, and a temperature coefficient of resonant frequency (τ_f) of −39.89 ppm/°C. A simulation of this Ca₃(BO₃)₂ sample as a dielectric substrate was conducted using HFSS to fabricate a microstrip patch antenna operating at 14.97 GHz, which exhibits a return loss (S₁₁) of −25.5 dB and a gain of 7.15 dBi. Full article

The absence of standardized evaluation criteria for cold patch asphalt mixtures (CPAMs) leads to arbitrary material selection in pavement pothole repair, resulting in premature failure and recurrent damage. This study develops a comprehensive evaluation framework combining macro-performance tests with X-ray computed tomography (CT)-based meso-structural analysis. The macroscopic evaluation system incorporates six key parameters: aggregate gradation, binder–aggregate ratio, penetration strength, molding strength, residual rate, and stability retention. The CT-based meso-structural assessment quantifies void characteristics (longitudinal distribution, radial distribution, fractal dimension) and aggregate skeleton features (contact points, coordination number) through 3D reconstruction. Experimental results demonstrate that optimizing asphalt content (4.5–4.7%) with adjusted critical aggregate fractions (4.75 mm:35.0–45.0%; 2.36 mm:30.0–40.0%; 13.2 mm:1.0–1.2%; 9.5 mm:10.0–15.0%) significantly enhances repair durability. The established multiscale evaluation methodology provides a theoretical foundation for developing standardized CPAM quality specifications, particularly in emergency maintenance scenarios. Full article

Cold mix asphalt (CMA) pothole repair is extensively utilized in time-sensitive highway maintenance due to its rapid deployment and all-weather applicability. However, premature failures caused by suboptimal construction practices under operational constraints (e.g., emergency repairs and adverse weather) necessitate frequent reworks, inadvertently escalating material consumption and associated environmental burdens. To address this challenge, this study proposes a quality-driven optimization framework integrating enhanced Analytic Hierarchy Process (AHP) and Grey Relational Analysis (GRA). The methodology systematically evaluates 18 technical parameters across six critical construction phases—grooving/molding, cleaning/drying, bonding layer application, material paving, compaction, and edge trimming—to identify dominant quality determinants. The analysis highlights material placement and compaction as the most significant phases in the repair process, with specific technical parameters such as compaction standardization, paving uniformity, compactor dimension selection, and material application emerging as key quality drivers. To assess the feasibility of the optimized process, a grey relational analysis was adopted to compare the proposed protocol with the cold-patch practices currently adopted by two municipal maintenance agencies in Shanghai, demonstrating superior alignment with an ideal repair benchmark. The developed model empowers highway agencies to achieve dual operational–environmental gains: maintaining urgent repair efficiency while mitigating secondary resource depletion through reduced repetitive interventions. Full article

As part of the Horizon 2020 InfraROB project aimed at enhancing road safety through innovative robotic solutions, a compact autonomous vehicle has been developed to repair asphalt potholes. Central to this system is a 3D printer capable of extruding a novel cold-asphalt mixture, specifically designed for patching road surfaces. The printer is mounted on a small robot that autonomously navigates to potholes, while the human operator controls the operation from a secure location outside the traffic area. The system’s development involved several key steps: designing the repair mixture, constructing the 3D printer for mixture extrusion, implementing a photogrammetric technique to accurately measure pothole geometry for printing, and integrating the extrusion system with the robotic platform. Two preliminary tests were conducted in controlled environments at Sapienza University of Rome to check the reliability of calculation of the amount of material needed to fill in the potholes. Finally, the entire procedure was tested on an Italian motorway, demonstrating the system’s functionality without encountering operational issues. Full article

Recently, there has been an increasing concern about the vulnerability of infrared object detectors to adversarial attacks, where the object detector can be easily spoofed by adversarial samples with aggressive patches. Existing attacks employ light bulbs, insulators, and both hot and cold blocks to construct adversarial patches. These patches are complex to create, expensive to produce, or time-sensitive, rendering them unsuitable for practical use. In this work, a straightforward and efficacious attack methodology applicable in the physical realm, wherein the patch configuration is simplified to uniform-sized grayscale patch blocks affixed to the object, is proposed. This approach leverages materials with varying infrared emissivity, which are easy to fabricate and deploy in the real world and can be long-lasting. We use a reinforcement learning approach to gradually optimize the patch generation strategy until the adversarial attack goal is achieved, which supports multi-gray scale patches and explores the effects of patch size and grayscale. The results of our experiments demonstrate the effectiveness of the method. In our configurations, the average accuracy of YOLO v5 in digital space drops from 95.7% to 45.4%, with an attack success rate of 68.3%. It is also possible to spoof the object detector in physical space. Full article

Construction and demolition waste (CDW) materials account for a considerable part of waste materials throughout the world. As these materials are not usually recycled, reusing them in construction projects is of major significance. In this study, recycled concrete, bricks, and glass were used as 100% aggregates of chip seal, which is a corrective or preventive pavement maintenance method. A cationic rapid setting (CRS-2) bitumen emulsion was also used to prepare the chip seal. Different tests, including the sand patch test, sweep test, British pendulum tester (BPT), interface bond, and Vialit test, were conducted. The results of these tests revealed that all these materials had sufficient aggregate embedment for vehicle speeds of more than 70 km/h, and the number of chips was less than 10%, indicating their good performance. All developed chip seals ranked as high skid resistance pavement at ambient temperature. The chip seals developed with concrete and glass showed the best adhesion with an asphalt pavement surface and an aggregate–bitumen adhesion at very cold and ambient temperatures due to the fact of their chemical compositions. Overall, using concrete aggregates to develop chip seals under different traffic loads is recommended. Finally, these findings can provide a novel approach for recycling CDW materials with low costs. Full article

Background: As a Class A bioterrorism agent, botulinum neurotoxin serotype A (BoNT/A) carries the risk of being used by terrorists to cause mass poisoning. The microneedle (MN) patch has a great potential for application as a novel vaccine delivery method. The aim of this study is to develop a thermally stable, dissolving microneedle patch for the delivery of a recombinant protein vaccine using a recombinant C-terminal heavy chain of BoNT/A (Hc of BoNT/A, AHc) to prevent botulism. Methods: Fish gelatin, a natural non-toxic and bacteriostatic material, was selected as the microneedle matrix for the preparation of the dissolving microneedle vaccine. Subsequently, the mechanical performance, bacteriostatic properties, vaccination effect, and stability of the microneedle patches were evaluated using instruments such as the displacement-force test station and optical coherence tomography (OCT) scanner. Results: Fish gelatin matrix at high concentrations has good bacteriostatic properties, and excellent mechanical performance and vaccination effect, meeting the necessities of a vaccine. In both in vivo and in vitro neutralization experiments, MN vaccines containing different antigen doses achieved the same protective efficacy as subcutaneous vaccinations, protecting mice against 10⁶ LD₅₀ of BoNT/A injected intraperitoneally. Thermal stability analysis of the MN vaccines revealed that the fish gelatin matrix protected the AHc vaccine from protein denaturation even after 7 days of storage at 37 °C and enabled the vaccine patches to maintain good immunogenicity and protective efficacy even after 6 months of storage at room temperature. Conclusion: In this study, we successfully prepared a bacteriostatic MN patch using a fish gelatin matrix that not only has a good vaccination effect, but also obviates the need for a cold chain for the AHc vaccine, providing the possibility of rapid, painless, and large-scale vaccination. Full article

At present, achieving good storability and water damage resistance remains challenging for cold-patching asphalt mixtures (CAMs). To address this issue, this study selects styrene–ethylene–butadiene–styrene copolymer (SEBS) and diesel as a modifier and diluent, respectively, to improve the water stability and storability of CAMs. The diesel oil content is determined through the Brookfield rotational viscosity test, and the modifier content is obtained through the Marshall stability test. With the empirical formula method, paper trail test, and modified Marshall test, mixed designs of CAMs modified with and without SEBS are established to determine the best cold-patching asphalt content. On this basis, the modification effect of SEBS is verified by comparing the test results of the modified and unmodified CAMs, and the water stability and Marshall stability tests are conducted before and after CAM storage, respectively. Results show that the optimum contents of SEBS and diesel oil are 7.5% and 40% of the base asphalt weight, respectively, and the best modified asphalt content is 4.6% of the mineral material weight in CAM. The Marshall residual stability and freeze–thaw splitting strength ratio of the 7.5% SEBS-modified CAM are increased by 20.1% and 15.7%, respectively, relative to the unmodified CAM, and the storage performance requirement of at least two months can be guaranteed. Full article

The hazards of plastic waste (PW) from polymers (e.g., polyethylene terephthalate (PET), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyvinyl chloride (PVC), nylon, polystyrene (PS), etc.), the mechanism of its spread in general, and its ubiquity in our daily lives as a continuously and/or frequently expelled product are a crisis of the twenty-first century, as reported by the United Nations in 2019, especially after the outbreak of the COVID-19 pandemic. This research included the process of modifying the rheological properties of asphalt to obtain asphalt suitable for use in a high-humidity atmosphere. The Iraqi climate is characterized by heat that reaches the point of harshness in the summer and coldness that falls below zero on some winter days. From this point of view, our recent study focuses mainly on making rheological and chemical modifications to asphalt using spent polymeric materials and used lubricating oils (ULO), thus achieving two important goals, namely obtaining asphalt with rheological properties resistant to the Iraqi atmosphere as well as eliminating both solid and liquid environmental pollutants. The microstructure and morphology of the designed patches were characterized using scanning electron microscopy (SEM) to indicate phase composition. Full article

Patching is one of the most common maintenance methods for potholes in roads. In order to improve the performance of cold-patching asphalt mixtures, an emulsified asphalt modified with waterborne epoxy resin was developed. Two waterborne epoxy resins and two curing agents were selected. The optimal experimental contents of the curing agents were obtained by measuring the compressive strength of the waterborne epoxy mortar (WEM) under different curing agent contents and curing period. The difference between the two waterborne epoxy resins was obtained by the flexural strength and stress–strain curves, which were measured by the modified bending test on the WEM. The evaluation method of the initial strength and forming strength of the waterborne epoxy emulsified asphalt mixture (WEEAM) was proposed by the experimental study of the compaction molding method and curing conditions. The high temperature performance, low temperature performance, and moisture susceptibility of the mixture were verified by comparing various kinds of WEEAM. The results show that using WEEAM as a road repair material has great advantages in improving pavement performance and road service levels. Full article

We present polymer nanocomposites of tungsten bronze nanorods (TBNRs) and ethylene propylene diene monomers (EPDM). The combination of these components allows the simultaneous enhancement in the mechanical and photothermal properties of the composites at low filler contents. The as-synthesized TBNRs had lengths and diameters of 14.0 ± 2.4 nm and 2.5 ± 0.5 nm, respectively, and were capped with oleylamine, which has a chemical structure similar to EPDM, making the TBNRs compatible with the bulk EPDM matrix. The TBNRs absorb a wide range of near-infrared light because of the sub-band transitions induced by alkali metal doping. Thus, the nanocomposites of TBNRs in EPDM showed enhanced photothermal properties owing to the light absorption and subsequent heat emission by the TBNRs. Noticeably, the nanocomposite with only 3 wt% TBNRs presented significantly enhanced tensile strain at break, in comparison with those of pristine EPDM, nanocomposites with 1 and 2 wt % TBNRs, and those with tungsten bronze nanoparticles, because of the alignment of the nanorods during tensile elongation. The photothermal and mechanical properties of these nanocomposites make them promising materials for various applications such as in fibers, foams, clothes with cold weather resistance, patches or mask-like films for efficient transdermal delivery upon heat generation, and photoresponsive surfaces for droplet transport by the thermocapillary effect in microfluidic devices and microengines. Full article

Aiming to solve the contradiction between the workability and performance of pothole patching using cold mixtures, this paper proposed new patching materials based on the microcapsule technique and polymer reinforcement, namely cold mixtures with polymer modified asphalt and dense graded (DG) of aggregates (PADG) mixtures. Laboratory tests were conducted to compare the PADG mixtures with commonly used DG mixtures and open graded (OG) mixtures concerning workability, storability, cohesion, stability, and durability of each mixture. The results found that the PADG mixtures were satisfactory in their workability and storability and were as satisfactory as the OG mixtures. Meanwhile, stability and durability of the PADG mixtures was better than the DG mixtures and OG mixtures, i.e., the PADG mixtures showed stability in the conditions of the timeliness, low temperature, and immersion, as well as the freeze-thaw resistance and wear resistance in wet conditions. Therefore, it can be concluded that PADG mixtures are applicable in timely and durable pothole repairs in low temperatures and wet conditions. Full article