Attenuation Mechanism Research Articles

Controllable fiberization engineering of cobalt anchored mesoporous hollow carbon spheres for positive feedback to electromagnetic wave absorption

In order to overcome the limitations of single attenuation mechanism materials in effectively absorbing electromagnetic waves (EMW), meticulous microstructural design of composites and an elevated degree of integration of wave absorbing mechanisms are crucial. Utilizing mesoporous hollow carbon spheres as precursors, PCHM@ComXn (X = Se, S, O) nano-microspheres were synthesized by anchoring cobalt nanoparticles on the surface, controllable encapsulating in continuous fiber structure by electrostatic spinning technique subsequently. The carbon shell-cavity core configuration interspersed with nanoparticles has the advantage of light weight, low density and extensive defects. Abundant heterogeneous interface in carbon fiber offers excellent electrical conductivity and high specific surface area, while a three-dimension conductive network optimizes the transmission loss to incident EMW. The efficient synergy of multiple mechanisms enables PCHM@CoSe2/CNFs to achieve a strong reflection loss of −50.55 dB at a matched thickness of 2.0 mm, while the EABmax value can be extended to a remarkable 6.80 GHz at 2.3 mm, which is considerably superior to fiber samples encapsulating other cobalt-based nanoparticles of the same family. This work provides an innovative direction for the development of high-performance EMW absorbers.

Numerical analysis and experimental study of membrane-type acoustic metamaterial plate with X-shaped pendulum arm and cylindrical mass blocks

Membrane-type acoustic metamaterials have a favorable noise suppression effect. Hence, a membrane-type acoustic metamaterial plate (MAML) with an X-shaped pendulum arm and cylindrical mass blocks (CMB) was proposed in this paper. The theoretical model based on spring–mass systems and numerical simulation models of the membrane-type acoustic metamaterial cell (MAMC) were established under fixed and periodic boundary conditions to reveal the noise attenuation mechanism quantitatively, and the necessity of the CMB is discussed. Based on the results, it can be observed that the normal displacement of the membrane is nearly zero when the noise frequency is at the peak of the sound transmission loss (STL) curve. However, when the frequency is at the valley of the STL curve, the displacement is nonzero and fluctuates significantly. Meanwhile, by comparing the STL curves with and without the CMB, it was found that the MAMC performance is improved effectively by the CMB at low frequencies. The effective mass density of MAMC was found to be negative. To verify the accuracy of numerical calculations, an impedance tube experiment was conducted. Finally, orthogonal experiments were designed to describe the effects of the structural parameters a, l, and t on the effective bandwidth [Formula: see text], peak frequency [Formula: see text], and comprehensive index [Formula: see text] and to obtain the optimal structural parameter combinations for different indexes. This work further contributes to applying and developing the membrane-type acoustic metamaterial.

The mutation of Japanese encephalitis virus envelope protein residue 389 attenuates viral neuroinvasiveness

The envelope (E) protein of the Japanese encephalitis virus (JEV) is a key protein for virus infection and adsorption of host cells, which determines the virulence of the virus and regulates the intensity of inflammatory response. The mutation of multiple aa residues in the E protein plays a critical role in the attenuated strain of JEV. This study demonstrated that the Asp to Gly, Ser, and His mutation of the E389 site, respectively, the replication ability of the viruses in cells was significantly reduced, and the viral neuroinvasiveness was attenuated to different degrees. Among them, the mutation at E389 site enhanced the E protein flexibility contributed to the attenuation of neuroinvasiveness. In contrast, less flexibility of E protein enhanced the neuroinvasiveness of the strain. Our results indicate that the mechanism of attenuation of E389 aa mutation attenuates neuroinvasiveness is related to increased flexibility of the E protein. In addition, the increased flexibility of E protein enhanced the viral sensitivity to heparin inhibition in vitro, which may lead to a decrease in the viral load entering brain. These results suggest that E389 residue is a potential site affecting JEV virulence, and the flexibility of the E protein of aa at this site plays an important role in the determination of neuroinvasiveness.

Experimental Observation of a New Attenuation Mechanism in hcp‐Metals That May Operate in the Earth's Inner Core

AbstractSeismic observations show the Earth's inner core has significant and unexplained variation in seismic attenuation with position, depth and direction. Interpreting these observations is difficult without knowledge of the visco‐ or anelastic dissipation processes active in iron under inner core conditions. Here, a previously unconsidered attenuation mechanism is observed in zinc, a low pressure analog of hcp‐iron, during small strain sinusoidal deformation experiments. The experiments were performed in a deformation‐DIA combined with X‐radiography, at seismic frequencies (∼0.003–0.1 Hz), high pressure and temperatures up to ∼80% of melting temperature. Significant dissipation (0.077 ≤ Q−1(ω) ≤ 0.488) is observed along with frequency dependent softening of zinc's Young's modulus and an extremely small activation energy for creep (⩽7 kJ mol−1). In addition, during sinusoidal deformation the original microstructure is replaced by one with a reduced dislocation density and small, uniform, grain size. This combination of behavior collectively reflects a mode of deformation called “internal stress superplasticity”; this deformation mechanism is unique to anisotropic materials and activated by cyclic loading generating large internal stresses. Here we observe a new form of internal stress superplasticity, which we name as “elastic strain mismatch superplasticity.” In it the large stresses are caused by the compressional anisotropy. If this mechanism is also active in hcp‐iron and the Earth's inner‐core it will be a contributor to inner‐core observed seismic attenuation and constrain the maximum inner‐core grain‐size to ≲10 km.

Impacts of LNAPL types on mechanisms and rate of natural source zone depletion

Understanding the mechanisms of natural source zone depletion (NSZD) will support an improved understanding of the long-term sustainability of NSZD as a site remedy and how NSZD rates may change over time. This is the first study that has quantified and compared the rate of three NSZD mechanisms (methanogenesis, vaporization, and aqueous biodegradation) between two chemically distinct light non-aqueous phase liquid (LNAPL) source zones (aliphatic-rich naphtha for Zone #1 vs aromatic-rich pyrolysis gasoline for Zone #2) within the same geologic and climate conditions. The rates of NSZD attributable to vaporization (400 mg C/m2/d vs. 300 mg C/m2/d) and aqueous biodegradation (92 mg C/m2/d vs. 67 mg C/m2/d) were similar for Zone #1 and #2; however, the rate of methanogenesis NSZD was 6x higher in Zone #1 (1000 mg C/m2/d vs. 170 mg C/m2/d). These results suggest that the aliphatic hydrocarbons content in an LNAPL source may be a factor in the rate of methanogenesis NSZD. For both Zone #1 and #2, total NSZD rate determined using this “three mechanism” measurement method was in reasonable agreement with two other methods used to measure total NSZD rates (CO2 Gradient Method and Dynamic Closed Chamber Method), validating the “three mechanism” method as a tool to measure the total NSZD rate at a site and to provide an improved understanding of the predominant NSZD mechanism. Overall, this study highlights the importance of LNAPL type and chemical characteristics in determining source zone natural attenuation mechanism and its total rates.

Constructing and optimizing epoxy resin-based carbon Nanotube/Barium ferrite microwave absorbing coating system

High-performance microwave absorbing coatings are highly indispensable for protecting human health and enhancing military strength. A single- and double-layer wave-absorbing coating system that employs complex microwave absorbers composed of the helical carbon nanotubes/doped barium ferrite composite with epoxy resin as the matrix was developed. The concentration and thickness of the coating were optimized by the numerical simulation and the adaptive genetic algorithm. The developed helical carbon nanotubes/doped barium ferrite wave-absorbing composites have a porous reticular structure, with abundant microscopic cavities and an adequately conductive network. The coatings are characterized by a flat surface, good uniformity, and high density. The reflectivity measured by the arch method is similar to that obtained through the finite element simulation, where the absorption bands of all the developed coatings are distributed in the range of 10–18 GHz. The optimized wave-absorbing coating exhibits the most uniform scattering pattern, the largest radar cross section (RCS) reduction, the smallest input reflection coefficient, and the highest absorptivity. Thus, it exhibits the best comprehensive microwave-absorption performance with a minimum reflection loss of −17.22 dB at 16.66 GHz. In particular, the absorption bandwidth of the coating can reach 9.16 GHz, which is attributable to its multiple synergistic electromagnetic attenuation mechanisms and its excellent characteristics of interference-cancellation and impedance-matching characteristics. Generally, helical carbon nanotubes/doped barium ferrite wave-absorbing coatings are promising candidates for applications in Ku-band microwave absorption.

Orbital Hybridization Induced Dipole Polarization and Room Temperature Magnetism of Atomic Co‐N4‐C toward Electromagnetic Energy Attenuation

AbstractManipulating the electronic structure and geometric coordination environment of single metal atoms has been considered as promising approach for enhancing dipole polarization and enriching electromagnetic attenuation mechanisms. However, achieving precise control of the dielectric polarization response at atomic scale remains a huge challenge. Herein, a metal‐acetate coordination complexes‐assisted strategy is proposed to prepare spatially isolated cobalt (Co) atoms embedded in accordion‐like nitrogen‐doped carbon (NC) matrix. The interactions between metal atoms and NC matrix are carefully tailored through the successive evolution of dispersion states of Co species, ranging from individual atoms to atomic clusters to nanoparticles. Density functional theory reveals that the orbital hybridization between the d electrons of embedded Co atoms and p electrons of coordinated N atoms induces the electron redistribution at N sites, enabling enhanced electric dipole polarization and robust room temperature magnetism (a saturation magnetization of 0.108 emu g−1 at 300 K). Consequently, Co‐SAs@NC exhibits optimal electromagnetic wave absorption properties with a minimum reflection loss of ‐54.4 dB and an effective absorption bandwidth of 8.4 GHz. This work demonstrates an efficient strategy for modulating electromagnetic response at atomic level and provides a novel insight into the d/p electrons orbital hybridization between single metal atoms and NC species.

Temperature regulated Fe3Si@SiC@carbon core-shell structure with high-performance microwave absorption

Developing high-performance microwave absorbing materials (MAMs) to address the electromagnetic wave pollution is still a huge challenge. Multi-interface core-shell structure with magnetic and dielectric loss components have been attracting extensive attention as MAMs for the enhanced interfacial polarization and impedance matching. In this work, magnetic loss core and dielectric loss bi-shell structure Fe3Si@SiC@C (FSC) composite was synthesized through hydrothermal, self-polymerizing coating and high temperature thermolysis. The thermal treatment temperature has a great effect on the morphology structure and electromagnetic properties of FSC. The results indicated that the FSC exhibited an effective absorption bandwidth (EAB) of 4.24 GHz at a thickness of 1.4 mm, and an EAB of 12.4 GHz with the absorber thickness varied from 1 mm to 3 mm. Furthermore, the microwave attenuation mechanism of the FSC composite were investigated in detail. The integration of magnetic core with multiple dielectric shells provides a design deliberation and reference for further high-performance MAMs fabrication.

SlCYP94B18 and SlCYP94B19 monooxygenases for the catabolic turnover of jasmonates in tomato leaves

(3R,7S)-Jasmonoyl-L-isoleucine (JA-Ile) is a plant hormone that regulates plant defense responses and other physiological functions. The mechanism of attenuation of JA-Ile signaling in the plant body is essential because prolonged JA-Ile signaling can be detrimental to plant survival. In Arabidopsis thaliana, the cytochrome P450 monooxygenases, CYP94B1/B3/C1, inactivate JA-Ile by converting it into 12-hydroxy-jasmonoyl-L-isoleucine (12-OH-JA-Ile), and CYP94C1 converts 12-OH-JA-Ile into 12-carboxy-jasmonoyl-L-isoleucine (12-COOH-JA-Ile). In the present study, we aimed to identify the cytochrome P450 monooxygenases involved in the catabolic pathway of JA-Ile in tomato leaves. Based on a gene expression screening of SlCYP94 subfamily monooxygenases using qPCR and the time-course of JA-Ile catabolism, we identified SlCYP94B18 and SlCYP94B19 expressed in tomato leaves as candidate monooxygenases catalyzing the two-step catabolism of JA-Ile. An in vitro enzymatic assay using a yeast expression system revealed that these enzymes efficiently converted JA-Ile to 12-OH-JA-Ile, and then to 12-COOH-JA-Ile. SlCYP94B18 and SlCYP94B19 also catalyzed the oxidative catabolism of several JA-amino acid conjugates (JA-AAs), JA-Leu and JA-Val, in tomatoes. These results suggest that SlCYP94B18 and SlCYP94B19 plays a role in the two-step oxidation of JA-AAs, suggesting their broad involvement in regulating jasmonate signaling in tomatoes. Our results contribute to a deeper understanding of jasmonate signaling in tomatoes and may help to improve tomato cultivation and quality.

Lightweight titanium dioxide/carbon nanotube composites prepared by atomic layer deposition for broad-band microwave absorption

The microwave absorbing material with appropriate impedance matching and excellent attenuation ability can be applied to resist electromagnetic radiation. In this work, carbon nanotubes were modified by titanium dioxide via the atomic layer deposition method, to prepare lightweight composites with high microwave absorption performance. The impedance matching and attenuation ability of titanium dioxide/carbon nanotube (TiO2/CNT) composites could be precisely controlled by adjusting the number of titanium dioxide deposition cycles. The relationship between the microstructure and microwave absorption performance of the composite was analyzed in detail. When the number of TiO2 deposition cycles was 100, the composite displayed outstanding microwave absorption performance, due to appropriate impedance matching and strong attenuation ability. The maximum effective absorption bandwidth of the composite reached 5.19 GHz (1.6 mm), which almost covered the Ku band. The microwave attenuation mechanism of the composite has also been investigated. This work provided a new idea for fabricating lightweight microwave absorption materials.

Mangroves as Natural Shields: A Comprehensive Review of Their Role in Mitigating Natural Disasters and Conservation Strategies

Mangrove ecosystems play a crucial role in mitigating the impact of natural disasters on coastal regions worldwide. This comprehensive review paper synthesizes multidisciplinary studies to explore the contribution of mangroves in reducing the risk of catastrophes such as storm surges, tsunamis, hurricanes, and coastal erosion. By analysing the complex relationships between mangroves and natural disasters, we delve into factors such as species composition, forest structure, hydrological regimes, and coastal geomorphology. Additionally, we investigate the socioeconomic implications of mangrove conservation and restoration efforts, highlighting their potential to enhance resilience and sustainable development in coastal communities. The paper presents a detailed examination of wave characteristics, types, and attenuation mechanisms, focusing on how mangrove features such as prop roots, knee roots, and pneumatophores influence wave dissipation. We discuss various numerical and statistical models used to predict wave attenuation through mangroves, providing insights into their strengths and limitations. Furthermore, we explore global and India-specific mangrove cover status, important species, and conservation measures, including legal frameworks and initiatives by governmental and non-governmental organizations. Finally, the review underscores the urgency of conserving and restoring mangrove ecosystems to safeguard both human well-being and ecological integrity in the face of escalating climate-related threats. It advocates for evidence-based decision-making and policy development in disaster risk management and climate adaptation, emphasizing the pivotal role of mangroves as natural shields against natural calamities. Overall, this paper contributes to the understanding of mangrove-mediated hazard reduction and provides guidance for maximizing the resilience of coastal communities in an increasingly volatile world.

Dynamic seismic signatures in a fluid‐saturated porous periodically layered medium considering effects of intrinsic anisotropy

AbstractThe interlayer wave‐induced fluid flow is an important mechanism for seismic attenuation and dispersion, as well as frequency‐dependent anisotropy, in the fluid‐saturated porous layered medium. This mechanism is closely related to the medium physical properties, and thus quantifying this mechanism is of significance for the seismic inversion of medium physical properties. Although numerous models have been proposed to quantify this mechanism, most models do not consider the effects of layer intrinsic anisotropy. To solve this problem, the effective complex‐valued and frequency‐dependent stiffness coefficients are derived for the fluid‐saturated porous medium composed of periodic transversely isotropic layers. Using the derived solutions, we study the effects of layer intrinsic anisotropy on seismic dispersion and attenuation, as well as frequency‐dependent anisotropy. It has been found that different matrix or fluid property contrasts between adjacent layers lead to different effects of intrinsic anisotropy. In addition, the effects of intrinsic anisotropy are also influenced by the fluid distribution when both matrix and fluid properties contrast among adjacent layers exist. In the low‐ and high‐frequency limits of wave‐induced fluid flow, our model reduces to the previous known results, which validates the correctness of our model. Our model can be applied in the seismic inversion of physical properties of reservoirs with intrinsic anisotropy, such as shale and tight sandstone reservoirs. In addition, our model can also be extended to cases with more complex intrinsic anisotropy and, thus, can be applied to complex anisotropic fractured reservoirs in the future.

Applying metabolic modeling and multi-omics to elucidate the biotransformation mechanisms of marine algal toxin domoic acid (DA) in sediments

Domoic acid (DA)-producing algal blooms are a global marine environmental issue. However, there has been no previous research addressing the question regarding the fate of DA in marine benthic environments. In this work, we investigated the DA fate in the water-sediment microcosm via the integrative analysis of a top-down metabolic model, metagenome, and metabolome. Results demonstrated that biodegradation is the leading mechanism for the nonconservative attenuation of DA. Specifically, DA degradation was prominently completed by the sediment aerobic community, with a degradation rate of 0.0681 ± 0.00954 d−1. The DA degradation pathway included hydration, dehydrogenation, hydrolysis, decarboxylation, automatic ring opening of hydration, and β oxidation reactions. Moreover, the reverse ecological analysis demonstrated that the microbial community transitioned from nutrient competition to metabolic cross-feeding during DA degradation, further enhancing the cooperation between DA degraders and other taxa. Finally, we reconstructed the metabolic process of microbial communities during DA degradation and confirmed that the metabolism of amino acid and organic acid drove the degradation of DA. Overall, our work not only elucidated the fate of DA in marine environments but also provided crucial insights for applying metabolic models and multi-omics to investigate the biotransformation of other contaminants.

Total Synthesis of Core 3 & Core 4‐Type Mucin Glycan Derivatives

AbstractRecent studies have demonstrated the ability of mucin O‐glycans to attenuate virulence in diverse, cross‐kingdom pathogens, sparking interest in their development as a novel therapeutic approach against infection. Although their virulence attenuating activity is evident, mucin glycans obtained from native sources comprise mixtures of several hundred distinct structures, and therefore the specific active glycan epitopes and molecular mechanisms of virulence attenuation remain unclear. Individual mucin glycan structures cannot be purified from native sources and are not amenable to automated synthesis; therefore, to further investigate the phenomena of virulence attenuation we have been developing convergent and scalable methods (>30 mg per target glycan) to assemble a mucin O‐glycan library in sufficient scale and purity to facilitate biological studies. Previously we described a method to obtain core 1 & core 2‐type mucin glycan derivatives that have since been used to identify active epitopes in Candida albicans and Vibrio cholerae. In the current study, we describe the expansion of our glycan library to include core 3 & core 4‐type derivatives, increasing the structural diversity of our platform for biological evaluation.

Weighted window attention and recover feature resolution-based network for deformable abdominal image registration

The Swin Transformer has attracted attention in the field of medical image analysis since its introduction in 2021 owing to its computational efficiency and long-range modeling capabilities. Because of these characteristics, the Swin Transformer can establish distant relationships between corresponding voxels at distant locations for complex abdominal image registration tasks. Transformer-based registration methods model the features of multiple fused voxels and output coarse-grained features of the same size. To enable the Transformer to output fine-grained information and strengthen the contribution of the Transformer in the registration model, we propose the recover feature resolution network (RFRNet), which converts the features outputted by the Transformer into fine-grained spatial information. In addition, fixed-window partitioning restricts the Transformer from modeling the global connection of semantic information with uncertain distances. Therefore, we proposed a weighted window attenuation (WWA) mechanism to achieve automatic global-scale interaction of window information after a window partitioning operation. Based on these improvements, we proposed a single-modal unsupervised deformable abnormal image registration model called RFR-WWANet. Qualitative and quantitative results showed that RFR-WWANet achieved significant improvements compared with the current state-of-the-art methods. Ablation experiments demonstrated the effectiveness of the RFRNet and WWA designs. Our code is available at https://github.com/MingR-Ma/RFR-WWANet.

Molybdenum disulfide modified silicon carbide ceramic nanofiber: Phase engineering for tuning microwave absorption properties of absorbers

Molybdenum disulfide (MoS2) is an important two-dimension multifunction material, which is widely used in semiconductor devices due to its special electrical properties. However, the electromagnetic wave absorption performance of MoS2 is severely limited as a result of the impedance mismatch between the material and free space. To address this issue, effective strategies of phase engineering and in situ growth techniques are employed to synthesize 2 H MoS2, 1 T/2 H MoS2, SiC@2 H MoS2, and SiC@1 T/2 H MoS2 composites. The electromagnetic absorbing property data reveal that the minimum reflection loss can reach 58.04 dB at 11.16 GHz in a 2.5 mm thick SiC@1 T/2 H MoS2 nanofiber coating; the effective absorbing bandwidth is up to 5.04 GHz (9.16–14.2 GHz). From the detailed analysis, it can be seen that the dielectric loss strength and the degree of impedance matching are the critical factors impacting the microwave absorption properties. The attenuation mechanisms underlying the excellent microwave absorption performance and related phenomena are explored, opening new directions for synthesizing MoS2-based electromagnetic wave absorbing materials with efficient and broadband.

Reversible Switching Between Microwave Absorption and EMI Shielding of VO2 Composite Foam.

Developing lightweight composite with reversible switching between microwave (MW) absorption and electromagnetic interference (EMI) shielding is promising yet remains highly challenging due to the completely inconsistent attenuation mechanism for electromagnetic (EM) radiation. Here, a lightweight vanadium dioxide/expanded polymer microsphere composites foam (VO2/EPM) is designed and fabricated with porous structures and 3D VO2 interconnection, which possesses reversible switching function between MW absorption and EMI shielding under thermal stimulation. The VO2/EPM exhibits MW absorption with a broad effective absorption bandwidth of 3.25GHz at room temperature (25 °C), while provides EMI shielding of 23.1dB at moderately high temperature (100 °C). This reversible switching performance relies on the porous structure and tunability of electrical conductivity, complex permittivity, and impedance matching, which are substantially induced by the convertible crystal structure and electronic structure of VO2. Finite element simulation is employed to qualitatively investigate the change in interaction between EM waves and VO2/EPM before and after the phase transition. Moreover, the application of VO2/EPM is demonstrated with a reversible switching function in controlling wireless transmission on/off, showcasing its excellent cycling stability. This kind of smart material with a reversible switching function shows great potential in next-generation electronic devices.

Experimental Study on the Boundary Reflection Effect of Stress Wave Propagation Based on the Newly Developed Test Apparatus

There is a ubiquitous boundary reflection effect of stress wave propagation in the indoor experimental studies. It is critical to improve the validity of waveform data by optimizing boundary materials to absorb reflection waves. In the present study, a calculation method for the optimal wave impedance of boundary materials was proposed based on the transmission and reflection principle of one-dimensional stress waves at the interface of different media. By using the calculation method, the optimal wave impedance value of the boundary material was obtained. A one-dimensional stress wave propagation test apparatus was developed for exploring the improvement effect of absorbing materials on the boundary reflection effect. One-dimensional stress wave propagation experimental studies in the complete red sandstone samples were carried out by setting various boundary absorbing materials such as pine pad, rubber pad, and steel pad. The results indicated that the experimental test results were consistent with the theoretical calculation results. In the stress wave propagation tests, the optimal wave impedance value of the boundary material was 1.12 × 106 kg/m2·s. When the pine pads were used as boundary absorbing materials, the suppression effect of boundary reflection effects is relatively the best. The present study provides references for analyzing the characteristics and mechanism of stress wave propagation and attenuation.

Average grain size evaluation using scattering-induced attenuation of coda waves

Grain size is one of the key microstructural factors affecting the mechanical properties of polycrystalline metal materials. In this study, a novel method for grain size evaluation using ultrasonic coda waves is proposed. Different from conventional bulk wave methods that require a point-by-point scanning of the structure, the proposed method allows for a rapid evaluation of the average grain size of the whole part from a single inspection location using one-pass testing data. A piecewise energy attenuation function dealing with different attenuation mechanisms is proposed to obtain the effective attenuation coefficient of coda waves. A power-law model is constructed to correlate the effective attenuation coefficient with the average grain size. Ultrasonic testing on nickel-based superalloy plate specimens with different average grain sizes is performed for model calibration and method verification. The applicability and robustness of the proposed method are further validated using a realistic turbine disk specimen with an irregular shape and non-uniform grain sizes. Results show that the proposed method yields a reliable and accurate estimation of the average grain size with a maximum relative error less than 20 %.

Simulating squirt flow in realistic rock models using graphical processing units (GPUs)

SUMMARY Understanding the underlying mechanisms of seismic attenuation and moduli dispersion in fluid-saturated cracked porous rocks is of great importance for the development of non-invasive methods to characterize the subsurface. Wave-induced fluid flow at the pore scale, so-called squirt flow, is responsible for seismic attenuation and moduli dispersion at sonic and ultra-sonic frequencies and may be relevant at seismic frequencies. The squirt flow associated attenuation is usually quantified using analytical models. However, numerical experiments suggest that the squirt flow related dissipation is sensitive to fine details of the pore geometry, which can only be modelled numerically. Most of the existing numerical studies explore this phenomenon using simplified models, and there is a lack of numerical studies that model the physics in realistic pore geometries with sufficient numerical resolution. As a result, the impact of wave-induced fluid flow on the effective static and time-dependent mechanical characteristics in realistic settings is still poorly understood. I address these issues by developing a numerical method to model the effective mechanical properties of a hydromechanically coupled system at the pore scale suitable for graphical processing units. A numerical evaluation of attenuation and modulus dispersion due to squirt flow in models based on 3-D microtomography images of cracked Carrara marble is presented. It is shown that the local hydraulic conductivity can be quantitatively estimated from the numerically evaluated effective properties. The accuracy of the numerical results is carefully analysed. This study improves the understanding of the underlying mechanisms of attenuation and moduli dispersion in fluid-saturated cracked rocks. The new method can be applied to model squirt flow for entire laboratory samples in the centimetre scale which was not possible a decade ago.