Small Density Research Articles

Lightweight multifunctional electromagnetic shielding composites achieved by depositing Ag@MXene hybrid particles on wood-based aerogel

As electronic devices become more integrated into daily life, concerns about electromagnetic radiation pollution become more severe, despite the increased portability they offer. Designing a lightweight and multifunctional material that is environmentally friendly, thermally conductive, and electromagnetically shielded is urgently needed. In this work, novel composites were fabricated by incorporating Ag@MXene hybrid particles into the wood-based aerogel. Compared with the aerogels containing only Ag nanoparticles (AgNPs) or MXene, the Ag@MXene/W aerogel exhibited more homogeneous dispersion of unfolded MXene nanosheets and more AgNPs but higher porosity (97.1 %) and smaller density (0.047 g cm−3). Consequently, the Ag@MXene/W aerogel exhibited high compressibility and low energy dissipation, remarkable strain sensitivity, impressive electrical conductivity (33.9 S m−1) and specific electromagnetic shielding efficiency (5765.96 dB cm2 g−1), and high thermal conductivity (0.81 W m−1 K−1). The excellent comprehensive performances ensure that the aerogel has wide applications in various fields, including electromagnetic pollution protection, strain detecting, and thermal management, etc.

Bending creep behaviour of various polymer films analysed by surface strain measurement.

Understanding the temporal bending deformation of polymer films is key to designing mechanically durable flexible electronic devices. However, such creep behaviour under persistent bending remains unclear due to a lack of precise and accurate bending strain analysis methods. Herein, we quantitatively analysed the bending creep behaviour of various polymeric films using our developed strain measurement method that can precisely measure surface strain from optical diffraction. The surface strain measurement reveals that bending creep deformation differs depending on the polymer structure. The four-element Burgers model was employed to model the temporal strain increase on the bending surface successfully. By fitting the four-element model to the time course of the measured surface strain, we found that each polymer film has a different threshold surface strain for the appearance of bending creep deformation. Such disparity in the bending creep behaviour can be explained by the difference in strain energy density between the polymer films and their elastic model; polymer films with a small strain energy density difference show small bending creep deformation. The results obtained in this study contribute to the elucidation of the bending creep behaviour of polymer films and the development of flexible electronic devices operated under persistent bending.

Giant amplification of Berezinskii-Kosterlitz-Thouless transition temperature in superconducting systems characterized by cooperative interplay of small-gapped valence and conduction bands

Two-dimensional superconductors and electron-hole superfluids in van der Waals heterostructures having tunable valence and conduction bands in the electronic spectrum are emerging as rich platforms to investigate novel quantum phases and topological phase transitions. In this work, by adopting a mean-field approach considering multiple-channel pairings and the Kosterlitz-Nelson criterion, we demonstrate giant amplifications of the Berezinskii-Kosterlitz-Thouless (BKT) transition temperature and a shrinking of the pseudogap for small energy separations between the conduction and valence bands and small density of carriers in the conduction band. The presence of the holes in the valence band, generated by intra-band and pair-exchange couplings, contributes constructively to the phase stiffness of the total system, adding up to the phase stiffness of the conduction band electrons that is boosted as well, due to the presence of the valence band electrons. This strong cooperative effect avoids the suppression of the BKT transition temperature for low density of carriers, that occurs in single-band superconductors where only the conduction band is present. Thus, we predict that in this regime, multi-band superconducting and superfluid systems with valence and conduction bands can exhibit much larger BKT critical temperatures with respect to single-band and single-condensate systems.

Research and Implementation of Denoising Algorithm for Brain MRIs via Morphological Component Analysis and Adaptive Threshold Estimation

The inevitable noise generated in the acquisition and transmission process of MRIs seriously affects the reliability and accuracy of medical research and diagnosis. The denoising effect for Rician noise, whose distribution is related to MR image signal, is not good enough. Furthermore, the brain has a complex texture structure and a small density difference between different parts, which leads to higher quality requirements for brain MR images. To upgrade the reliability and accuracy of brain MRIs application and analysis, we designed a new and dedicated denoising algorithm (named VST–MCAATE), based on their inherent characteristics. Comparative experiments were performed on the same simulated and real brain MR datasets. The peak signal-to-noise ratio (PSNR), and mean structural similarity index measure (MSSIM) were used as objective image quality evaluation. The one-way ANOVA was used to compare the effects of denoising between different approaches. p < 0.01 was considered statistically significant. The experimental results show that the PSNR and MSSIM values of VST–MCAATE are significantly higher than state-of-the-art methods (p < 0.01), and also that residual images have no anatomical structure. The proposed denoising method has advantages in improving the quality of brain MRIs, while effectively removing the noise with a wide range of unknown noise levels without damaging texture details, and has potential clinical promise.

Kinetic plasma-sheath self-organization

The interaction between a plasma and a solid surface is studied in a (1D–1V) kinetic framework using a localized particle and convective energy source. Matching the quasineutral plasma region and sheath horizon is addressed in the fluid framework with a zero heat flux closure. It highlights non-polytropic nature of the physics of parallel transport. Shortfalls of this approach compared to a reference kinetic simulation highlight the importance of the heat flux as the measure of kinetic effects. Non-collisional closure and higher moment closure are used to determine the sound velocity. Within these frameworks, no gain in the fluid predictive capability is obtained. The kinetic constraint at the sheath horizon is discussed and modified to account for conditions that are actually met in simulations, namely quasineutrality with a small but finite charge density. Analyzing the distribution functions shows that collisional transfer is mandatory to achieve steady-state self-organization on the open field lines.

High-resolution single-pixel imaging based on a probe of single-mode fiber and hybrid multimode fiber

In single-pixel imaging, the combination of random speckles generated by the multimode fiber (MMF) as projection patterns and the compressed sensing theory is beneficial for improving imaging performance and expanding application scenarios. However, the image reconstruction quality using the MMF is usually unsatisfactory, which is helpless for retrieving objects with detailed information or multi-resolution objects. The reason lies in the limited number and compromised spatial resolution of low-correlated speckle patterns provided by the MMF in practical circumstances like long operating time or bending disturbances. Here, we propose a novel concept of hybrid multimode fibers (HMMF) for single-pixel imaging resolution enhancement. Based on the bending insensitivity property of single-mode fiber (SMF) and the compatibility property of small bending radius and high mode density of HMMF, the wavelength-modulated SMF-HMMF probe is designed to significantly improve the number and spatial resolution of speckle patterns while ensuring the robustness of the imaging system. The experimental results demonstrate that the spatial resolution of the speckle patterns has been improved by approximately 3 times (from 20.35 pixels to 7.24 pixels) compared to the non-HMMF probe. The correlation of the speckle patterns holds as low as about 0.1, even when the tuning wavelength interval is reduced to 5 pm. The maximum deviation of the repeatability of the speckle pattern was 0.044 for the 120-min interval tested, and the consistent output of the speckle pattern under various bending configurations demonstrates the strong robustness of the imaging system. High-quality imaging of multi-resolution target objects has been achieved even at a remarkably low sampling rate (SR) of 5 %. This study has the potential to expand the application of single-pixel imaging systems in flexible and long-distance detection imaging scenarios.

Role of Interaction Range and Buoyancy on the Adhesion of Vesicles.

Vesicles on substrates play a fundamental role in many biological processes, ranging from neurotransmitter release at the synapse on small scales to the nutrient intake of trees by large vesicles. For these processes, the adsorption or desorption of vesicles to biological substrates is crucial. Consequently, it is important to understand the factors determining whether and for how long a vesicle adsorbs to a substrate and what shape it will adopt. Here, we systematically study the adsorption of a vesicle to planar substrates with short- and long-range interactions, with and without buoyancy. We assume an axially symmetric system throughout our simulations. Previous studies often considered a contact potential of zero range and neutral buoyancy. The interaction range alters the location and order of the adsorption transition and is particularly important for small vesicles, e.g., in the synapse. Whereas even small density differences between the inside and the outside of the vesicle give rise to strong buoyancy effects for large vesicles, e.g., giant unilamellar vesicles, as buoyancy effects scale with the fourth power of the vesicle size. We find that (i) an attractive membrane-substrate potential with nonzero spatial extension leads to a pinned state, where the vesicle benefits from the attractive membrane-substrate interaction without significant deformation. The adsorption transition is of first order and occurs when the substrate switches from repulsive to attractive. (ii) Buoyancy shifts the transversality condition, which relates the maximal curvature in the contact zone to the adhesion strength and bending rigidity, up/downward, depending on the direction of the buoyancy force. The magnitude of the shift is influenced by the range of the potential. For upward buoyancy, adsorbed vesicles are at most metastable. We determine the stability limit and the desorption mechanisms and compile the thermodynamic data into an adsorption diagram. Our findings reveal that buoyancy, as well as spatially extended interactions, are essential when quantitatively comparing experiments to theory.

Quantifying the turbulent mixing driven by the Faraday instability in rotating miscible fluids

The effect of the rotation on the turbulent mixing of two miscible fluids of small contrasting density, induced by Faraday instability, is investigated using direct numerical simulations. We quantify the irreversible mixing, which depicts the conversion of the available potential energy (APE) to the background potential energy (BPE) through the irreversible mixing rate M. We demonstrate that at lower forcing amplitudes, the turbulent kinetic energy (t.k.e.) increases with an increase in the Coriolis frequency f till (f/ω)2<0.25, where ω is the forcing frequency, during the sub-harmonic instability phase. This enhancement of t.k.e. is attributed to the excitement of more unstable modes. The irreversible mixing sustains for an extended period with increasing (f/ω)2 till 0.25 owing to the prolonged sub-harmonic instability phase and eventually ceases with instability saturation. When (f/ω)2>0.25, the Coriolis force significantly delays the onset of the sub-harmonic instabilities. The strong rotational effects result in lower turbulence because the bulk of the APE expends to BPE, decreasing APE that converts back to t.k.e. reservoir for (f/ω)2>0.25. Therefore, in the subsequent oscillation, the t.k.e. available to contribute to the external energy input from periodic forcing is small. Since the instability never saturates for (f/ω)2>0.25, the conversion of APE to BPE via M continues, and we find prolonged irreversible mixing. At higher forcing amplitudes, the instability delaying effect of rotation is negligible, and the turbulence is less intense and short-lived. Therefore, the irreversible mixing phenomenon also ends quickly for (f/ω)2<0.25. However, when (f/ω)2>0.25, a continuous irreversible mixing is observed. We also examine the mixing efficiency in terms of M and find that the mixing is efficient at lower forcing amplitudes and rotation rates of (f/ω)2>0.25 because the major portion of APE expends to BPE.

Reconstruction refinement of hybrid background-oriented schlieren tomography

This paper introduces a hybrid method that leverages the advantages of both the window-based separate algorithm and the regularization-based unifying algorithm to refine the three-dimensional refractive index field measured by the background-oriented schlieren (BOS) tomography. Two image-warping approaches, under paraxial and non-paraxial ray-tracing assumption, are developed as a connecting link between coarse and refined reconstruction. An orthogonal test is conducted to examine the influence of various factors on the reconstruction fields in the hybrid approach, providing insights into the impact of factors such as the ray-tracing assumption, initial value for refractive index iteration, and image displacement algorithm. Various synthetic and real BOS cases demonstrate that our hybrid method reconstructs a more detailed and robust field, outperforming conventional BOS reconstruction methods in scenarios with small or large density gradients, as well as laminar or turbulent structures.

Reference intervals for cardiometabolic risk factors in China: a national multicenter cross-sectional study on an adult population sample.

The reference intervals (RIs) of adult blood lipid parameters currently used in China are not derived from the results of research in local populations and have not been adjusted for age and sex. In this study, we aimed to determine accurate RIs for blood lipid parameters and blood glucose (GluG) for Chinese adults using a national multicenter study. A total of 11,333 adults between 18 and 90 years of age were recruited in seven representative regions in China between June 2020 and December 2020. Hospitals participating in the study were regrouped into two geographical regions, southern China (Changsha, Chengdu, Hangzhou, and Nanning) and northern China (Beijing, Shenyang, and Ningxia), according to their geographical and administrative location. All samples were freshly collected and measured collectively in one laboratory on the Mindray full Automatic biochemical analyzer chemistry BS2000 analytical systems. Outliers were removed using the Tukey test. Three-level nested analysis of variance and scatter plot were used to explore the variations in sex, age, and region. Percentile curves of each indicator were plotted using the least mean square (LMS) method. The lower limit (2.5th percentile) and the upper limit (97.5th percentile) of the RI were determined by using nonparametric statistical methods. We also calculated the 90% confidence interval (CI) for the lower and upper limits. A total of 8,283 participants were enrolled in the final analysis, with 3,593 (43.4%) men and 4,690 (56.6%) women. Regionality was observed in three analytes [small dense low density lipoprotein cholesterol (sd-LDLC), GluG, and apolipoprotein A1 (ApoA1)]. In northern China, the sd-LDLC and GluG levels in Shenyang were significantly higher than those in Ningxia and Beijing (P<0.05). In southern China, the sd-LDLC and GluG levels in Nanning were significantly higher than those in the three other cities (P<0.05), whereas the sd-LDLC and GluG levels in Chengdu were significantly lower than those in the three other cities (P<0.05). The level of ApoA1 in Chengdu was significantly higher than that in the three other cities. The homocysteine (HCY) level in male participants was clearly higher than that in female participants [ratio of standard deviation (SDR)sex =0.56], whereas the levels of high density lipoprotein cholesterol (HDLC) (SDRsex =0.40) and ApoA1 (SDRsex =0.27) in males were lower. The GluG and HCY level increased gradually with age. In females aged 45-55 years, there was an interesting change in scatter charts, where triglyceride (TG) and total cholesterol (TC) increased rapidly. We also found that for the age group of >55 years, the levels of TG and TC in females gradually surpassed those in males. The findings of this study may help establish age- and sex-specific reference values for the blood lipids of Chinese adults and serve as a valuable guide for the screening, diagnosis, treatment, prevention, and monitoring of cardiovascular disease (CVD).

High performance field emission cathode based on the diamond nanowires prepared by nanocrystalline diamond films annealed in air

This paper reports the field emission (FE) characteristics of a diamond nanowires (DNWs) array. The nanocrystalline diamond (NCD) film was deposited on silicon by microwave plasma chemical vapor deposition (MPCVD) and then annealed in air forming DNWs and hydrogenated at last. A high-field flat-plate emission test structure with a 1.03 μm gap between anode and cathode was prepared and the electrical properties proved it feasible. The FE performance of DNWs array was measured in a vacuum test system and that of NCDs film as a comparison. Finally, their FE parameters were analyzed and extracted based on the Fowler–Nordheim (F-N) theory. The results show that transforming NCDs film into DNWs array can improve the FE characteristics greatly. The turn-on field is as low as 1.36 V μm−1 dropping by one order of magnitude, while the field enhancement factor and FE current density are up to 156.68 and 484.75 mA cm−2 respectively rising both by two orders of magnitude. This excellent FE performance stems from the characteristics of large aspect ratio, very small tip radius and high density of DNWs.

İzmir Yöresi Zeytin Bahçe Topraklarının Karbon ve Azot Stokları

Soil organic carbon (SOC) and total nitrogen (TN) have a very important role in sustainable soil quality, crop production, and environmental impacts, and determining of carbon nitrogen ratio (C: N ratio) is very important for creating data banks in terms of ecosystem functions. Plants influence the interaction of SOC and TN, as well as ecosystem yield and the continental carbon cycle. Climate, atmosphere, and land-use change are all included in numerical models of the carbon (C) and nitrogen (N) cycles. This study was conducted to determine the SOC and TN stocks, the C: N ratio and their relationships with the soil properties of olive orchards in Aliaga, Bayindir, Bergama, Dikili, Foca, Karaburun, Kemalpasa, Menderes, Menemen, Odemis, Seferihisar, Selcuk, Tire, Torbali and Urla provinces of Izmir in Turkey. For this purpose, 129 soil samples were taken from 0-30 cm depth. The texture, pH, EC, lime, OM, SOC and TN content and stocks, Bulk density (Db) was determined. Db and C: N ratio varied between 0.84-1.31 g cm-3, 5.17-80.50, and SOC density and stocks changed between 4.00-53.00 mg cm-3, 1.25-1.59 kg m-2, N density and stocks between 0.09-2.66 mg cm-3, 0.03-0.80 kg m-2, respectively. The highest BD was obtained from Tire, the highest SOC stocks from Karaburun, the highest TN from Seferihisar and Karaburun. The very small bulk density which is negatively associated with OM and clay is an important feature. The SOC contents were higher in relatively heavy rainfall regions. SOC and soil texture have a strong relationship. As a result, texture, precipitation, temperature, soil depths, and regeneration of soil affect the SOC and TN stocks. The results may be effective in terms of sustainable soil quality and ecosystem functions for olive cultivation.

Design Strategies towards Advanced Hydrogen Evolution Reaction Electrocatalysts at Large Current Densities.

Hydrogen (H2), produced by water electrolysis with the electricity from renewable sources, is an ideal energy carrier for achieving a carbon-neutral and sustainable society. Hydrogen evolution reaction (HER) is the cathodic half-reaction of water electrolysis, which requires active and robust electrocatalysts to reduce the energy consumption for H2 generation. Despite numerous electrocatalysts have been reported by the academia for HER, most of them were only tested under relatively small current densities for a short period, which cannot meet the requirements for industrial water electrolysis. To bridge the gap between academia and industry, it is crucial to develop highly active HER electrocatalysts which can operate at large current densities for a long time. In this review, the mechanisms of HER in acidic and alkaline electrolytes are firstly introduced. Then, design strategies towards high-performance large-current-density HER electrocatalysts from five aspects including number of active sites, intrinsic activity of each site, charge transfer, mass transfer, and stability are discussed via featured examples. Finally, our own insights about the challenges and future opportunities in this emerging field are presented.

Process qualification, additive manufacturing, and postprocessing of a hydrogen peroxide/kerosene 6 kN aerospike breadboard engine

This contribution addresses the complete process chain of an annular aerospike breadboard engine fabricated by laser powder bed fusion using the nickel-based superalloy Inconel® 718. In order to qualify the material and process for this high-temperature application, an extensive material characterization campaign including density and roughness measurements, as well as tensile tests at room temperature, 700, and 900 °C, was conducted. In addition, various geometric features such as triangles, ellipses, and circular shapes were generated to determine the maximum unsupported overhang angle and geometrical accuracy. The results were taken into account in the design maturation of the manifold and the cooling channels of the aerospike breadboard engine. Postprocessing included heat treatment to increase mechanical properties, milling, turning, and eroding of interfaces to fulfill the geometrical tolerances, thermal barrier coating of thermally stressed surfaces for better protection of thermal loads, and laser welding of spike and shroud for the final assembly as well as quality assurance. This contribution goes beyond small density cubes and tensile samples and offers details on the iterations necessary for the successful printing of large complex shaped functional parts. The scientific question is how to verify the additive manufacturing process through tensile testing, simulation, and design iterations for complex geometries and reduce the number of failed prints.

Recording ten-fold larger IKr conductances with automated patch clamping using equimolar Cs+ solutions.

Background: The rapid delayed rectifier potassium current (IKr) is important for cardiac repolarization and is most often involved in drug-induced arrhythmias. However, accurately measuring this current can be challenging in human-induced pluripotent stem cell (hiPSC)-derived cardiomyocytes because of its small current density. Interestingly, the ion channel conducting IKr, hERG channel, is not only permeable to K+ ions but also to Cs+ ions when present in equimolar concentrations inside and outside of the cell. Methods: In this study, IhERG was measured from Chinese hamster ovary (CHO)-hERG cells and hiPSC-CM using either Cs+ or K+ as the charge carrier. Equimolar Cs+ has been used in the literature in manual patch-clamp experiments, and here, we apply this approach using automated patch-clamp systems. Four different (pre)clinical drugs were tested to compare their effects on Cs+- and K+-based currents. Results: Using equimolar Cs+ solutions gave rise to approximately ten-fold larger hERG conductances. Comparison of Cs+- and K+-mediated currents upon application of dofetilide, desipramine, moxifloxacin, or LUF7244 revealed many similarities in inhibition or activation properties of the drugs studied. Using equimolar Cs+ solutions gave rise to approximately ten-fold larger hERG conductances. In hiPSC-CM, the Cs+-based conductance is larger compared to the known K+-based conductance, and the Cs+ hERG conductance can be inhibited similarly to the K+-based conductance. Conclusion: Using equimolar Cs+ instead of K+ for IhERG measurements in an automated patch-clamp system gives rise to a new method by which, for example, quick scans can be performed on effects of drugs on hERG currents. This application is specifically relevant when such experiments are performed using cells which express small IKr current densities in combination with small membrane capacitances.

Three-dimensional radiation hydrodynamics simulations of wandering intermediate-mass black holes considering the anisotropic radiation and dust sublimation

ABSTRACT By performing three-dimensional radiation hydrodynamics simulations, we study Bondi–Hoyle–Lyttleton accretion on to intermediate-mass black holes (BHs) wandering in the dusty gas. Here, we take into account the anisotropic radiation feedback and the sublimation of dust grains. Our simulations show that when the relative velocity between the BH and the gas is small ($\sim 20\rm\, km~s^{-1}$) and gas density is $\sim 10^4 \rm cm^{-3}$, the gas mainly accretes from near the equatorial plane of the accretion disc at a time-averaged rate of 0.6 per cent of the Bondi–Hoyle–Lyttleton rate. An ionized region like two spheres glued together at the equatorial plane is formed, and the dense shock shell appears near the ionization front. The BH is accelerated at $\sim 10^{-8}\, \rm cm~s^{-2}$ due to the gravity of the shell. For denser gas ($\sim 10^6 \rm cm^{-3}$), the time-averaged accretion rate is also 0.6 per cent of the Bondi–Hoyle–Lyttleton rate. However, the BH is decelerated at $\sim 10^{-7}\, \rm cm~s^{-2}$ due to gravity of the dense downstream gas although the dense shock shell appears upstream. Our simulations imply that intermediate-mass BHs in the early universe keep floating at $\gtrsim {\rm several}\, 10\, \rm km~s^{-1}$ without increasing mass in interstellar gas with density of $\sim 10^4\, \rm cm^{-3}$, and slow down and grow into supermassive BHs in galaxies with the density of $\sim 10^6\, \rm cm^{-3}$.

Some qualitative analyses on a vegetation-water model with cross-diffusion and internal competition

This paper is concerned with a vegetation-water model with cross-diffusion and intra-plant competitive feedback under Neumann boundary conditions. First, we found that the equilibrium with small vegetation density is always unstable, and if the cross-diffusion coefficient is suitably large, the equilibrium with relatively large vegetation density loses its stability, and Turing instability occurs. A priori estimates of positive steady-state solutions are also established by the maximum principle of elliptic equations. Moreover, some qualitative analyses on the steady-state bifurcations for both simple and double eigenvalues are conducted in detail. Space decomposition and the implicit function theorem are used for double eigenvalues. In particular, the global continuation is obtained, and the result shows that there is at least one non-constant positive steady-state solution when cross-diffusion is large. Finally, numerical simulations are provided to prove and supplement theoretic research results, and some vegetation patterns with the increase of the soil water diffusion feedback intensity are formed, where the transition appears: gap [Formula: see text] stripe [Formula: see text] spot.

Applying Characteristic Impedance Compensation Cut-Outs to Full Radio Frequency Chains in Multi-Layer Printed Circuit Board Designs.

Modern wireless communication systems are of utmost importance to various sectors such as healthcare, education, the household, and the advancement of emerging technologies like the internet of things, autonomous vehicles, and the enhancement of 5G. Further development and improvement of these systems drives the need for small dimension, high integration and density, and cost-effective electronic devices. Achieving optimal performance in wireless electronic devices involves overcoming engineering challenges related to microstrip line signal integrity. This research addresses the impact of surface mount technology (SMT) component pads on signal integrity, proposing a novel high-frequency microstrip line structure for mitigating impedance discontinuities. The study introduces stepped microstrip lines and explores characteristic impedance compensation techniques. A six-layer printed circuit board (PCB) structure is presented, and the effects of compensation on signal integrity are analyzed using time-domain reflectometry and scattering parameter measurements. The results demonstrate the effectiveness of compensation methods in aligning characteristic impedance with desired values, thereby ensuring improved impedance matching and transmission coefficients. The average over-the-length impedance for the proposed structure with compensation applied was measured to be 52.7 Ω, which is only 1.3 Ω (2.5%) more than that of the reference microstrip. Applying reference plane cut-outs leads to a maximum compensated absolute value of more than 30 Ω to reach the target impedance with a 10% tolerance. This research contributes valuable insights for advancing wireless communication systems and maintaining robustness in high-frequency microstrip transmission lines.

Numerical Modeling of Composite Load-Induced Seabed Response around a Suction Anchor

Suction anchors play a crucial role as marine supporting infrastructure within mooring systems. In engineering practice, the composite load comprising nonlinear waves and cyclic pull-out loads can have adverse effects on the seabed soil, posing a threat to the pull-out bearing capacity of the suction anchor. While existing research predominantly focuses on cyclic pull-out loads, the influence of nonlinear wave actions at the seabed surface remains overlooked. This study employs a two-dimensional integrated numerical model to investigate the dynamic soil response around a suction anchor under the influence of both nonlinear waves and cyclic pull-out loads, focusing on the mechanisms that lead to liquefaction and the deterioration of the interfacial friction due to the excess pore pressure buildup. The numerical results reveal that the cyclic pull-out load is the primary factor in the deterioration of the frictional resistance at the suction–soil interface, especially when the pull-out load is inclined with the suction anchor. Parametric studies indicate that the relative difference in frictional resistance deterioration between cases considering and excluding surface water waves becomes more pronounced in soils characterized by a small consolidation coefficient (Cv) and relative density (Dr).

Effects of rolling processing on the microstructures, mechanical properties and strain softening behavior of biodegradable Zn-0.06 Mg alloy

Micro-alloyed Zn–Mg alloys have attracted extensive attention in the field of medical implant due to their excellent biosafety and moderate degradation rate. The low Mg content could compromise the improvement of strength, therefore, the appropriate rolling process was investigated to enchance strength and inhibit strain softening behavior of Zn-0.06 Mg alloy. The observed changes in microstructures, mechanical properties, and strain softening behavior of the as-cast alloy after three different rolling processing were consistent with those exhibited by the solid-solution alloy. The cold rolled alloys showed excellent strength due to their small average grain size and high initial dislocation density, however, they also exhibited noticeable strain softening behavior. Hot rolling processing can result in coarsening of the grains, reduction in dislocation density and introducing a large number of twins, which inhibited strain softening behavior but also leaded to a decrease in the strength compared with cold rolling. The hot-cold rolling processing can induce the formation of heterostructure, wherein coarse grains encircled fine grains, while high density dislocation regions and low density dislocation regions were uniformly distributed, which effectively inhibited strain softening behavior on the basis of maintaining good mechanical properties.