Search Results (56)

Soft organic gels are commonly used as tissue phantoms for experiments. In the mimic ultrasound imaging field, researchers are developing approaches to modify the acoustic properties of the gels. Introducing oil liquids and hard solid particles are two common methods to tune acoustic and mechanical properties of the soft gels. In this work, the acoustic wave energy loss mechanisms were studied in detail on Agar gel with both micro-Graphite and nano-Alumina particles. Via experimental measurements, the results show that the effective acoustic energy loss is comparable in these two recipes. However, temporal pulse elongation and scattering behaviors were distinguishable. To understand the sound attenuation mechanism in detail, numerical simulations in controlled conditions were conducted, from wavelengths longer than the particle diameter to wavelengths shorter than particles, and we compared perfect bonding and insufficient bonding between the hard particles surrounding gels. Comparing the experimental observations and numerical simulation results, the Agar gel with nano-Alumina presents stronger dispersion-induced energy loss than the Agar gel with micro-Graphite. On the contrary, the Agar gel with micro-Graphite shows more significant scattering-induced destructive interferences than the Agar gel with nano-Alumina. Full article

The demand for earth construction, primarily driven by environmental considerations, is currently growing. Earth, as a building material, has a very low carbon footprint and is easily recyclable, promoting a circular economy. It is also valued for its intrinsic qualities such as hygrothermal properties, air quality, acoustic performance, and esthetics. To meet this demand and promote earth construction, a better understanding of the local resources is essential. However, not all soils are suitable for earth construction, and their properties can significantly influence the final material performance. The assessment of soil suitability for earth construction requires both scientific rigor and practical field applicability. This study evaluates the correlation between traditional field-testing methods and standardized laboratory analyses through a comprehensive characterization of 39 soils from the Nouvelle-Aquitaine region in France. The research methodology integrated different field tests commonly used by practitioners, including sensory evaluations, plasticity tests, and cohesion assessments, with five standardized geotechnical tests covering particle size distribution, Atterberg limits, methylene blue value, organic matter content, and density measurements. The particle size distribution analysis revealed diverse soil compositions, with clay-sized particle content (<0.002 mm) ranging from 5% to 75%. Strong correlations were established between field and laboratory results, particularly between the cigar test and plasticity index (R² = 0.8863), and between ring test scores and clay-sized particle content percentages, validating the reliability of traditional testing methods. Plasticity indices varied from 0% to 50%, indicating different soil behaviors and potential applications. These correlations demonstrate that while traditional field tests provide reliable preliminary assessment tools, laboratory testing remains essential for final material validation. The results demonstrate that while several soils are directly suitable for various earth construction techniques, other soils falling outside conventional recommendation envelopes may still be suitable for specific construction techniques when appropriately evaluated and may require modification through sieving, mixing, or stabilization. Full article

Modified basalt microfiber-reinforced polyurethane elastomer composites were prepared by a semi-prepolymer method with two different silane coupling agents (KH550 and KH560) in this study. Infrared spectroscopy was used to quantify the degree of microphase separation and analyze the formation of hydrogen bonding in polyurethane. The interfacial surface and the morphology of fibers and composites from tensile fracture were examined by a scanning electron microscope. Further measurements were performed on an electronic universal testing machine for characterizing the mechanical properties of composites. Moreover, the loss factor and transmission loss of composite materials were obtained from dynamic thermomechanical analysis and acoustic impedance tube, respectively. The suitable concentrations in the modification of basalt fibers were established at 1% for KH550 and 1.5% for KH560. The best overall performance was obtained in KH550-BMF/PUE group, as the properties increased by 31% in tensile strength, 37% in elongation at break, and 21% in acoustic insulation. Full article

Katydids employ acoustic signals to communicate with others of their species and have evolved to generate sounds by coupling the anatomical structures of their forewings. However, some species have evolved to implement an additional resonance mechanism that enhances the transmission and sound pressure of the acoustic signals produced by the primary resonators. Secondary resonators, such as burrow cavities or horn-shaped structures, are found in the surrounding environment but could also occur as anatomical modifications of their bodies. Chamber-like structures have been described in species of katydids with modified pronota or wings. It has been shown that these modified structures directly affect the transmission and filtering of acoustic signals and can function as a Helmholtz resonator that encapsulates the primary sound source. By morphological and acoustic analysis, we describe a new genus of Conocephalinae and investigate the physical properties of their sound production structures for three new species from the Andes of Colombia and Ecuador. Males of the new genus, here described as Tectucantus n. gen., have a characteristic inflated pronotum enclosing the reduced first pair of wings and extending rearward over the first abdominal segments. We test the hypothesis that the pronotal cavity volume correlates with the carrier frequency of specific calls. The cavity of the pronotal chamber acts as a Helmholtz resonator in all three Tectucantus species and, potentially, in other distantly related species, which use similar secondary body resonators. Full article

Metamaterials enable the modulation of elastic waves or acoustic waves in unprecedented ways and have a wide range of potential applications. This paper achieves the simultaneous manipulation of surface elastic waves (SEWs) and surface acoustic waves (SAWs) using two-dimensional acousto-elastic metamaterials (AEMMs). The proposed AEMMs are composed of periodic hollow cylinders on the surface of a semi-infinite substrate. The band diagrams and the frequency responses of the AEMMs are numerically calculated through the finite element approach. The band diagrams exhibit simultaneous bandgaps for the SEWs and SAWs, which can also be effectively tuned by the modification of AEMM geometry. Furthermore, we construct the AEMM waveguide by the introduction of a line defect and hence demonstrate its ability to guide the SEWs and SAWs simultaneously. We expect that the proposed AEMMs will contribute to the development of multi-functional wave devices, such as filters for dual waves in microelectronics or liquid sensors that detect more than one physical property. Full article

Background: Pharmacologically targeting the STING pathway offers a novel approach to cancer immunotherapy. However, small-molecule STING agonists face challenges such as poor tumor accumulation, rapid clearance, and short-lived effects within the tumor microenvironment, thus limiting their therapeutic potential. To address the challenges of poor specificity and inadequate targeting of STING in breast cancer treatment, herein, we report the design and development of a targeted liposomal delivery system modified with the tumor-targeting peptide iRGD (iRGD-STING-PFP@liposomes). With LIFU irradiation, the liposomal system exploits acoustic cavitation, where gas nuclei form and collapse within the hydrophobic region of the liposome lipid bilayer (transient pore formation), which leads to significantly enhanced drug release. Methods: Transmission electron microscopy (TEM) was used to investigate the physicochemical properties of the targeted liposomes. Encapsulation efficiency and in vitro release were assessed using the dialysis bag method, while the effects of iRGD on liposome targeting were evaluated through laser confocal microscopy. The CCK-8 assay was used to investigate the toxicity and cell growth effects of this system on 4T1 breast cancer cells and HUVEC vascular endothelial cells. A subcutaneous breast cancer tumor model was established to evaluate the tumor-killing effects and therapeutic mechanism of the newly developed liposomes. Results: The liposome carrier exhibited a regular morphology, with a particle size of 232.16 ± 19.82 nm, as indicated by dynamic light scattering (DLS), and demonstrated low toxicity to both HUVEC and 4T1 cells. With an encapsulation efficiency of 41.82 ± 5.67%, the carrier exhibited a slow release pattern in vitro after STING loading. Targeting results indicated that iRGD modification enhanced the system’s ability to target 4T1 cells. The iRGD-STING-PFP@liposomes group demonstrated significant tumor growth inhibition in the subcutaneous breast cancer mouse model with effective activation of the immune system, resulting in the highest populations of matured dendritic cells (71.2 ± 5.4%), increased presentation of tumor-related antigens, promoted CD8+ T cell infiltration at the tumor site, and enhanced NK cell activity. Conclusions: The iRGD-STING-PFP@liposomes targeted drug delivery system effectively targets breast cancer cells, providing a new strategy for breast cancer immunotherapy. These findings indicate that iRGD-STING-PFP@liposomes could successfully deliver STING agonists to tumor tissue, trigger the innate immune response, and may serve as a potential platform for targeted immunotherapy. Full article

This article presents a metal matrix composite material consisting of NiTi wires embedded in nitrile butadiene rubber (NBR) that preserves NBR’s inherent acoustic characteristics while enabling acoustic modification through the NiTi phase transition induced by stress and temperature. The macroscopic mechanical parameters of transversely isotropic NiTi-NBR composite materials are derived by means of a secondary bridging model that takes into account interfacial phases. On this basis, the acoustic impedance properties and absorption coefficient of composite materials were examined as a function of NiTi volume fraction using the transfer matrix method. The accuracy and effectiveness of the theoretical method were verified by comparing the calculated results with finite element simulation. The research results indicated that regulating the volume fraction of NiTi can lead to the anticipated value of the input impedance of composite materials, improving impedance matching with media like water and rubber, which offers novel insights and a theoretical foundation for the development of underwater sound-absorbing materials. Full article

Hailfall is a severe local weather event that can cause great economic losses as well as the loss of people’s property; however, it is still difficult for domestic meteorological stations to comprehensively observe hail, and domestic independently developed hail observation instruments are still scarce. To help enable better automatic hail observations, a new independently developed hailstone disdrometer based on the acoustic principle, which can be used to measure the hailstone number and particle size and to calculate the corresponding equivalent liquid precipitation of hailstones, is proposed in this paper. The characteristics of hailstones were preliminarily analyzed using observation data from two hailstone disdrometers installed in Aksu, Xinjiang, where three hail events were observed via the hailstone disdrometer in the summer of 2023. By analyzing the development of deep convection clouds using the Fengyun 4A satellite-based cloud-top brightness temperature, and synoptic conditions based on the fifth-generation global climate reanalysis dataset produced by the European Centre for Medium-Range Weather Forecasts (the ECMWF ERA5 dataset), the hail formation mechanism was investigated in detail for one hailfall event. Accurate hail observations are an important basis for understanding spatiotemporal hail variation. The hailstone disdrometer proposed in this study offers a useful approach for domestic hail observation to provide first-hand hail information for the inspection of weather modification effects and disaster prevention and reduction. Full article

The purpose of this study is to use acoustic emission (AE) technology to explore the changes in the interface and mechanical properties of GF/VER composite materials after being treated with NaOH and to analyze the optimal modification conditions and damage propagation process. The results showed that the GF surface became rougher, and the number of reactive groups increased after treating the GF with a NaOH solution. This treatment enhanced the interfacial adhesion between the GF and VER, which increased the interfacial shear strength by 25.31% for monofilament draw specimens and 27.48% for fiber bundle draw specimens compared to those before the GF was modified. When the modification conditions were a NaOH solution concentration of 2 mol/L and a treatment time of 48 h, the flexural strength of the GF/VER composites reached a peak value of 346.72 MPa, which was enhanced by 20.96% compared with before the GF was modified. The process of damage fracture can be classified into six types: matrix cracking, interface debonding, fiber pullout, fiber relaxation, matrix delamination, and fiber breakage, and the frequency ranges of these failure mechanisms are 0~100 kHz, 100~250 kHz, 250~380 kHz, 380~450 kHz, 450~600 kHz, and 600 kHz and above, respectively. This paper elucidates the fracture process of GF/VER composites in three-point bending. It establishes the relationship between the AE signal and the interfacial and force properties of GF/VER composites, realizing the classification of the damage process and characterizing the mechanism. The frequency ranges of damage types and failure mechanisms found in this study offer important guidance for the design and improvement of composite materials. These results are of great significance for enhancing the interfacial properties of composites, assessing the damage and fracture behaviors, and implementing health monitoring. Full article

The behavior of the EK-181 low-activation ferritic-martensitic reactor steel (Fe–12Cr–2W–V–Ta–B) in the states with different levels of strength and plastic properties after traditional heat treatment (THT) and after high-temperature thermomechanical treatment (HTMT) in the temperature range from −196 to 25 °C, including the range of its cold brittleness (ductile–brittle transition temperature, DBTT) is studied. The investigations are carried out using non-destructive acoustic methods (internal friction, elasticity) and transmission and scanning electron microscopy methods. It is found that the curves of temperature dependence of internal friction (the vibration decrement) of EK-181 steel after THT and HTMT are similar to those of its impact strength. Below the ductile–brittle transition temperature, it is characterized by a low level of dislocation internal friction. The temperature dependence curves of the steel elastic modulus increase monotonically with the decreasing temperature. In this case, the value of Young’s modulus is structure-sensitive. A modification of the microstructure of EK-181 steel as a result of HTMT causes its elastic modulus to increase, compared to that after THT, over the entire temperature range under study. The electron microscopic studies of the steel microstructure evolution near the fracture surface of the impact samples (in the region of dynamic crack propagation) in the temperature range from −196 to 100 °C reveal the traces of plastic deformation (increased dislocation density, fragmentation of the martensitic structure) at all of the temperatures under study, including those below the cold brittleness threshold of EK-181 steel. Full article

The use of solid particles as direct heat absorbance and storage media promises enhanced storage densities in concentrated solar power (CSP) technologies. The long-term optical performance of those particles, which aim to be operational over years, is crucial. Dry powder coating with a deep black Cu-Mn-oxide pigment in a resonant acoustic mixer and subsequent sintering was employed to improve the long-term optical performance of hematite-rich spherical particles, which aimed to replace the state-of-the-art bauxite proppants. Due to the specific reactivity of the hematite particles, a new strategy using an Al-modified composition of the initial deep black pigment was required. The Al modification diminishes cation diffusion into hematite, allowing the formation of spinel-type Fe-Mn-Cu-Al-oxide coatings with favorable long-term temperature and optical stability. The effect of chemical composition of the coating layer on the coating process mechanism was discussed and the need for an elongated sintering time was noticed to ensure the termination of stable spinel phase formation. The structural and optical measurements revealed the enhancement of the properties of hematite absorber particles through this new modified coating process. Full article

Acoustical properties of various materials were analyzed in order to determine their potential for the utilization in the three-dimensional printing process of stringed musical instruments. Polylactic acid (PLA), polyethylene terephthalate with glycol modification (PET-G), and acrylonitrile styrene acrylate (ASA) filaments were studied in terms of sound reflection using the transfer function method. In addition, the surface geometry parameters (Sa, Sq, Sz, and Sdr) were measured, and their relation to the acoustic performance of three-dimensional-printed samples was investigated. It was found that a higher layer height, and thus a faster printing process, does not necessarily mean poor acoustical properties. The proposed methodology also proved to be a relatively easy and rapid way to test the acoustic performance of various materials and the effect of three-dimensional printing parameters to test such a combination at the very beginning of the production process. Full article

Porous structures with light weight and high mechanical performance exist widely in the tissues of animals and plants. Biomimetic materials with those porous structures have been well-developed, and their highly specific surfaces can be further used in functional integration. However, most porous structures in those tissues can hardly be entirely duplicated, and their complex structure-performance relationship may still be not fully understood. The key challenges in promoting the applications of biomimetic porous materials are to figure out the essential factors in hierarchical porous structures and to develop matched preparation methods to control those factors precisely. Hence, this article reviews the existing methods to prepare biomimetic porous structures. Then, the well-proved effects of micropores, mesopores, and macropores on their various properties are introduced, including mechanical, electric, magnetic, thermotics, acoustic, and chemical properties. The advantages and disadvantages of hierarchical porous structures and their preparation methods are deeply evaluated. Focusing on those disadvantages and aiming to improve the performance and functions, we summarize several modification strategies and discuss the possibility of replacing biomimetic porous structures with meta-structures. Full article

A low-cost custom-made pseudo-anthropomorphic lung phantom, offering a model for ultrasound-guided interventions, is presented. The phantom is a rectangular solidstructure fabricated with polyvinyl alcohol cryogel (PVA-C) and cellulose to mimic the healthy parenchyma. The pathologies of interest were embedded as inclusions containing gaseous, liquid, or solid materials. The ribs were 3D-printed using polyethylene terephthalate, and the pleura was made of a bidimensional reticle based on PVA-C. The healthy and pathological tissues were mimicked to display acoustic and echoic properties similar to that of soft tissues. Theflexible fabrication process facilitated the modification of the physical and acoustic properties of the phantom. The phantom’s manufacture offers flexibility regarding the number, shape, location, and composition of the inclusions and the insertion of ribs and pleura. In-plane and out-of-plane needle insertions, fine needle aspiration, and core needle biopsy were performed under ultrasound image guidance. The mimicked tissues displayed a resistance and recoil effect typically encountered in a real scenario for a pneumothorax, abscesses, and neoplasms. The presented phantom accurately replicated thoracic tissues (lung, ribs, and pleura) and associated pathologies providing a useful tool for training ultrasound-guided procedures. Full article

The modification of interatomic distances due to high pressure leads to exotic phenomena, including metallicity, superconductivity and magnetism, observed in materials not showing such properties in normal conditions. In two-dimensional crystals, such as graphene, atomic bond lengths can be modified by more than 10 percent by applying in-plane strain, i.e., without generating high pressure in the bulk. In this work, we study the strain-induced Mott transition on a honeycomb lattice by using computationally inexpensive techniques, including the Gutzwiller Wave Function (GWF) and different variants of Gutzwiller Approximation (GA), obtaining the lower and upper bounds for the critical Hubbard repulsion (U) of electrons. For uniaxial strain in the armchair direction, the band gap is absent, and electron correlations play a dominant role. A significant reduction in the critical Hubbard U is predicted. Model considerations are mapped onto the tight-binding Hamiltonian for monolayer graphene by the auxiliary Su–Schrieffer–Heeger model for acoustic phonons, assuming zero stress in the direction perpendicular to the strain applied. Our results suggest that graphene, although staying in the semimetallic phase even for extremely high uniaxial strains, may show measurable signatures of electron correlations, such as the band narrowing and the reduction in double occupancies. Full article