Shear Force Research Articles

Hierarchically‐Interlocked, Three‐Axis soft Iontronic Sensor for Omnidirectional Shear and Normal Forces

AbstractArtificial tactile sensing capable of measuring shear and normal forces is crucial for the diverse human‐machine interactions and dexterous robotic manipulations. However, existing soft multi‐axis force sensors usually suffer from limited detectable directions and complex coupling mechanisms, limiting their applications in realistic wearable and robotic systems. Here, a hierarchically‐interlocked, three‐axis soft iontronic sensor is presented with an asymmetrical electrode pattern that leverages the mortise‐and‐tenon structure and ultracapacitive principle to detect omnidirectional shear and normal forces. The designed sensor facilitates the decoupling process and achieves enhanced sensing performances including high accuracy, fast response ability, and mechanical robustness. Prototypical integration and application of the sensor are demonstrated to perform wearable telecontrol of virtual platforms and assist robot gripper through closed‐loop force feedback. A sensing array is further developed to construct a touch panel and identify handwriting based on the continuously measured directions of applied forces. This work may offer a potentially promising solution for the next‐generation intelligent electronic skins requiring multimodal tactile sensing information.

Effect of Different Salinities on the Biochemical Properties and Meat Quality of Adult Freshwater Drum (Aplodinotus grunniens) During Temporary Rearing.

Salinity is a significant environmental component that affects the physiological state of aquatic species. This study aimed to investigate whether water salinity had an impact on the biochemical properties and meat quality of adult Aplodinotus grunniens during temporary rearing of 7 days. Salinity caused increased osmotic pressure and antioxidant enzyme activities of Aplodinotus grunniens, which were attributed to the increase in the content of alanine and glutamate. It raised the hardness and shear force with an increase in salinity, leading to an increase in water-holding capacity. Salinity enhanced the DHA ratio with a decrease in the atherosclerotic index and thrombosis index. Combined with the increase in flavor amino acids and nucleotides, salinity enhanced the umami taste of Aplodinotus grunniens. These findings suggest that temporary rearing in salinity might be a practical approach to improving the meat quality of adult Aplodinotus grunniens.

Seismic response control of shear frame structure using a novel tuned-mass type composite column

Concrete filled steel tube (CFST) column is widely applied in shear frame structure in seismic-prone area owing to its superior earthquake resistant performance. However, CFST column might still suffer damage under a severe earthquake. This paper proposes a novel tuned-mass type column-in-column (CIC) system to improve the seismic behavior of the CFST column and hence protect the structure. The CIC system is formed by splitting the CFST column into a primary column and a secondary column, while the overall cross section area and hence the load-bearing capacity is not changed. By optimally selecting the springs and dashpots to interconnect the two columns, the CIC can act as a non-conventional tuned mass damper (TMD) to reduce seismic vibrations of structures. To demonstrate the proposed CIC concept, a single-story and a five-story frame structure with and without control are designed. Nonlinear time history analyses are performed to study the seismic responses of these structures considering different seismic design levels, earthquake ground motions and CIC control schemes. Numerical results show that the CIC system can effectively reduce the seismic induced story acceleration, displacement and drift ratio of frame structures with the reduction ratios approximately between 21 % and 30 %, and the ratios on reducing the base shear force and bending moment are between 27 % and 31 %, and between 34 % and 49 %, respectively. The proposed CIC control concept is a new solution for mitigations of seismic responses of CFST frame structures.

A review on rheological approaches as a perfect tool to monitor thermal degradation of biodegradable polymers

AbstractThis review provides an in-depth analysis of the thermal degradation of biodegradable polymers through rheological methods. Focusing on key techniques such as time sweep tests, frequency sweep tests, and nonlinear rheological analyses gained at higher shear tests, the review highlights how these approaches offer critical insights into polymer stability and degradation kinetics. It entails an understanding of how molecular weight reduction, a common degradation mechanism, significantly impacts the performance of biodegradable polymers, and how the use of appropriate fillers can enhance thermal stability by mitigating chain scission. The review also discusses the application of the Arrhenius equation in modelling thermal degradation, helping predict degradation rates and optimize processing conditions. Time sweep tests are particularly emphasized for their ability to monitor polymer stability under various environmental conditions, while frequency sweep tests provide insights into the effects of processing/thermal history on material degradation. Tests at higher shear rates, which simulate real-world processing conditions such as extrusion and injection moulding, are explored for their role in understanding how processing-induced shear forces accelerate polymer degradation. Various biodegradable polymers are considered in this review, with polylactic acid (PLA) being the dominant polymer studied across most research, providing a clear picture of its degradation behaviour and strategies for enhancing its thermal stability. Therefore, it is expected that this review will be a comprehensive guide for researchers and engineers looking to optimize the thermal stability and performance of biodegradable polymers in various industrial applications. Graphical abstract

Dietary Tributyrin Improves Growth Performance, Meat Quality, Muscle Oxidative Status, and Gut Microbiota in Taihe Silky Fowls under Cyclic Heat Stress.

Heat stress adversely affects poultry production and meat quality, leading to economic losses. This study aimed to investigate the effects of adding tributyrin on growth performance, meat quality, muscle oxidative status, and gut microbiota of Taihe silky fowls under cyclic heat stress (CHS) conditions. In this study, 120-day-old Taihe silky fowls (male) were randomly divided into six dietary treatments. These treatments included a normal control treatment (NC, fed a basal diet), a heat stress control treatment (HS, fed a basal diet), and HS control treatments supplemented with 0.04%, 0.08%, 0.16%, and 0.32% tributyrin, respectively. The NC treatment group was kept at 24 ± 1 °C, while the HS treatment birds were exposed to 34 ± 1 °C for 8 h/d for 4 weeks. Results showed that CHS decreased growth performance and compromised the meat quality of broilers (p < 0.05). However, tributyrin supplementation improved ADG and FCR in broilers exposed to CHS (p < 0.05). Additionally, tributyrin supplementation resulted in increased shear force value and GSH-Px activity, as well as a decrease in drip loss, ether extract content, and MDA content of the breast muscle in broilers under CHS (p < 0.05). Furthermore, tributyrin supplementation up-regulated the mRNA expressions of Nrf2, NQO1, HO-1, SOD, and GSH-Px of the breast muscle in broilers exposed to CHS (p < 0.05). Based on these positive effects, the study delved deeper to investigate the impact of 0.16% tributyrin supplementation (HS + 0.16%T) on the cecum microbiota. The HS + 0.16%T treatment showed an increase in the relative abundance of Rikenellaceae_RC9_gut_group (p < 0.05) and a trend towards an increase in Lactobacillus (p = 0.096) compared to the HS treatment. The results indicate that supplementation successfully improved the growth performance and meat quality of Taihe silky fowls. Furthermore, tributyrin supplementation, particularly at levels of 0.16%, improved meat quality by enhancing muscle antioxidant capacity, which is believed to be associated with activation of the Nrf2 signaling pathway.

Biomechanical Analysis of Rectus Femoris Kinesio Taping Effects on Post-Muscle Fatigue Stop-Jump Task Performance

Objectives: This study aims to compare the effects of kinesio tape (KT) on the rectus femoris muscle in athletes and novices under pre- and post-fatigue conditions. Methods: Nineteen male volunteers took part, and fatigue was assessed using the Borg CR10 Scale. Kinematic and kinetic data were collected using Vicon MX13+ infrared cameras (250 Hz) and Kistler force platforms (1500 Hz), respectively. Visual 3D v5.0 software analyzed the data, focusing on parameters like angular displacement, ground reaction forces (GRFs), impulse, and joint moments during a stop-jump task. A two-way mixed-design ANOVA was used to assess group, fatigue, and KT effects. Results: There was a significant effect after applying KT. The results showed significant differences in knee flexion range of motion (ROM), hip flexion moment, vertical impulse, and peak vertical GRFs between pre- and post-fatigue conditions (all p &lt; 0.05). The trained group exhibited less knee valgus ROM, higher hip flexion velocity at initial contact, and prolonged time to peak proximal tibia anterior shear force. Conclusions: KT application was found to reduce lower limb loading, improve force acceptance and joint stability, and alleviate fatigue-induced disparities. These findings highlight the potential of KT in enhancing lower limb strength and performance, particularly under fatigue.

Friction-Induced Near-Infrared Emission and Its Mechanism.

Triboluminescence (TL) is an optical phenomenon in which light is emitted from the surface of a material when subjected to pressure or shear forces. Due to its potential applications in non-destructive testing, radiation sources, and spectroscopic probes, TL has garnered increasing attention over the past two decades. However, experimental observations in the infrared spectrum remain limited, and its emission mechanism has not yet been fully understood. In this study, significant emission in the near-infrared spectrum was experimentally observed from the tribo-pairs of Cr/YSZ and quartz/YSZ. The results indicate that the Tribo-Induced Near-Infrared Light Emission consists of three peaks, in which the 780 nm peak is related to the electronic transition between the 3d5/2 and 3d3/2 orbitals of Y3+ ions, while the 880 nm and 990 nm peaks can be attributed to hole centers and T-type centers in the intrinsic defects of YSZ, respectively. Additionally, experiments reveal that the Cr/YSZ tribo-pair exhibits a redshift of 11-18 nm at the 780 nm peak compared to the quartz/YSZ tribo-pair. To explain the cause of the redshift phenomenon, X-ray photoelectron spectroscopy and UV-Vis absorption spectroscopy were used to measure the energy level spacing between the 3d5/2 and 3d3/2 orbitals of Y3+ and the bandgap width of YSZ before and after friction, respectively. We found that the bandgap width of the doped YSZ decreases after friction, which is often accompanied by a reduction in the energy level spacing between the 3d5/2 and 3d3/2 orbitals of Y3+. The extent of the reduction in energy level spacing varies with different dopants, leading to the redshift phenomenon.

Investigation of Churn and Annular Flow Transition Boundaries in Vertical Upward Gas-Water Two-Phase Flow

ABSTRACT Flow patterns in two-phase flow in vertical upward pipes are crucial for predicting phase distribution, flow transitions, and stability. Existing studies on churn to annular flow transitions primarily focus on flow rates, physical parameters, pressure, and temperature, often overlooking pipe diameter. This study addresses this gap using a multiphase pipe flow experimental setup to examine transitions under varying pipe diameters, gas flow rates, and liquid flow rates. Results show that with a constant liquid flow rate, increasing pipe diameter requires a higher gas flow rate to form annular flow, leading to greater pressure gradients and smoother fluctuations. Conversely, with a constant gas flow rate, larger pipe diameters decrease the liquid flow rate needed for annular flow, resulting in smaller pressure gradients and smoother fluctuations. Smaller pipe diameters make annular flow formation easier, with smaller pressure gradients but larger fluctuations. A novel churn-annular flow transition boundary model was developed, considering factors like gas shear force, surface tension, gravity, viscous force, and pressure gradient. Evaluated with 804 experimental data sets, the new model’s prediction accuracy exceeds 98.19%, outperforming traditional models with 53.92%-86.27% accuracy, enhancing applicability across varying diameters.

Performance-based seismic design of controlled rocking reinforced concrete frame with beam-end hinge

This study investigates the seismic performance of the Controlled Rocking Reinforced Concrete Frame with Beam-end Hinge (CR-RCFB) system. The novelty of our research lies in the development and validation of a finite element model that accurately predicts the dynamic response of CR-RCFB structures under various seismic conditions, specifically focusing on the innovative use of joint stiffness ratios and the integration of dampers. A finite element model was developed and validated through shaking table tests. The research examined the dynamic responses of the CR-RCFB under ten ground motion records, varying the node relative stiffness ratios. The interstory displacement amplification coefficient (α) was found to range between 1.08 and 1.20, while the earthquake-reduction coefficient (β) varied from 0.8 to 0.3 depending on the stiffness ratio. Results indicate that node stiffness ratios between 0.01 and 0.25 optimize performance, minimizing peak interstory displacement and base shear response. Additionally, integrating dampers increased the damping ratio from 14.48% to 30.51%, enhancing energy dissipation by shifting absorption from plastic deformation to damper yield. Pushover analysis was used to recalculate and validate the parameters α and β, demonstrating that the integration of dampers effectively controls displacement response. These findings suggest that the CR-RCFB system with integrated dampers offers enhanced seismic resilience by reducing displacement and base shear forces compared to traditional reinforced concrete frames.

Heterochain entanglements forced by shear forces and their influence on the properties of polylactic acid/hydrogenated styrene‐ethylene‐butylene‐styrene tri‐block copolymers blends

AbstractA forced entanglement between polylactic acid (PLA) chains and hydrogenated styrene‐ethylene‐butylene‐styrene (SEBS) tri‐block copolymers chains is designed based on the inertia of PLA to shear force and the sensitivity of SEBS to shear force. The melt blending of PLA with SEBS prepared through a twin‐screw extruder is a strategic method to form interchain entanglements. The influence of star‐shaped SEBS (s‐SEBS) and linear SEBS (l‐SEBS) on the compatibility, crystallization behavior, tensile properties, and rheological characteristics is systematically investigated. The incompatible interfaces between PLA and s‐SEBS or l‐SEBS are confirmed by their interfacial tension and micrographs of their cryo‐fractured surfaces. Although the interfacial incompatibility in PLA/s‐SEBS blends and PLA/l‐SEBS blends, s‐SEBS, or l‐SEBS could effectively enhance their crystallization behavior, tensile ductility and dynamic rheological properties. Relative to the Newtonian behavior of PLA, PLA/SEBS blends exhibit obvious shear‐thinning behavior under frequency‐dependent conditions, which clarifies the physical entanglements of PLA/SEBS blends. PLA/s‐SEBS blends possess stronger heterogeneous entanglements than PLA/l‐SEBS blends, which is verified by the micrographs of cryo‐fractured surfaces, crystallization characteristics, and rheological behavior. This designed concept based on the chain dynamics in the processing provides clues for polymer blends with significantly different sensitivity of chains to shear force to improve their properties.Highlights The melt blending of PLA with SEBS prepared through a twin‐screw extruder. The forced entanglement between PLA chain and SEBS chain is designed. PLA/s‐SEBS blends have stronger heterogeneous entanglement. The addition of SEBS can enhance its crystallization behavior and toughness. PLA/SEBS blends exhibit show shear‐thinning behavior in frequency dependence.

A preliminary biomechanical assessment and user perceptions of a motorized lifter for patient transfer

ABSTRACT A “no-lift” policy in healthcare discourages manual patient lifting to reduce worker injuries. This study explores modifications to a floor lift (NEAR-1) to align with this policy. NEAR-1 features a shorter lower lifting arm and a redesigned sling, enabling patients to (a) transfer in a sitting position, unlike a floor lift’s semi-reclining position, and (b) feel more in control by removing the sling’s rotational degree of freedom and letting the patient’s feet rest on the lifter base. The device also reduced patient weight-bearing, compared to sit-to-stand lifts. Biomechanical analysis was done to map the risk to the nurses and capture the patient’s experience with the modified lift (NEAR-1). Thirteen subjects carried out patient transfer tasks using both the NEAR-1 and the manual transfer approach, and this comparison will provide the baseline data for future systematic reviews. From the results, NEAR-1 significantly reduced the L5-S1 compression, the mediolateral shear forces, and the anteroposterior shear forces, with the exception of the muscle activities in the lower back, the shoulder, and the biceps. Moreover, patients felt safer and more comfortable with the device. Overall, the NEAR-1 lifter presents a biomechanically beneficial and user-friendly option for patients with limited weight-bearing capability.

Preservation of chicken breast meat by ginger extract and ginger essential oil

The study aims to extend the shelf-life of chicken breast meat by different treatments, including: (i) ratio of ginger: water = 60:40, 70:30 and 80:20; (ii) ginger essential oil 6%, 10% and 14%; (iii) edible coatings formula (sodium alginate combined with ginger extract or ginger essential oil). The research evaluated the effect of these treatments on the physicochemical parameters (pH, color, shear force, drip loss) and microbiological indicators (E. coli and aerobic plate count) of chicken breast meat during the cooling storage. The results showed that the physicochemical parameters of chicken breast meat were not affected by different treatments, these parameters were well maintained during cooling storage (4 &amp;plusmn; 1&amp;deg;C). Moreover, the ginger extract 70%, ginger essential oil 10% and the combination of ginger with an edible coating positively inhibit the growth of microorganisms. The total aerobic and E. coli plate count of samples, which were treated by these treatments, decreased within 7-10 days of cooling storage. Moreover, the chicken breast meat was treated with sodium alginate-ginger essential oil 10% had E. coli and the aerobic microbial plate count was within Vietnamese National Standards (TCVN 12429- 3:2021) during ten days of cooling storage.

Seismic isolation design of high-rise shear wall structures in high-intensity areas

Taking a shear wall structure in a high-intensity area of 20 floors as an example, the seismic reduction scheme of the structure was determined, and the Etabs software was used to conduct time history analysis on the seismic and non-seismic structures. The floor shear force, overturning moment, and short-term surface pressure of the isolation support were obtained. The results showed that under frequent earthquake action, the average maximum floor shear force in the X direction of the isolated upper structure was only about 28 % of that of the non-isolated structure. The maximum inter story shear ratio was 0.34, and the maximum floor shear force in the Y direction was only about 25 % of that of the non-isolated structure. The maximum inter story shear ratio was 0.31. The average maximum overturning moment of the upper structure in the X direction after isolation is about 30 % of that of the non-isolated structure. The maximum overturning moment ratio is 0.36, and the average overturning moment of the maximum floor in the Y direction is about 22 % of that of the non-isolated structure. The maximum overturning moment ratio is 0.26. Under rare earthquake action, the maximum inter story displacement angles in the X and Y directions of each floor of the seismic isolation structure are 1/302 and 1/446, respectively. The maximum surface pressure value of the isolation bearing under rare earthquake is 28.9 MPa, the minimum surface pressure value is 5.58 MPa, and the maximum displacement is 579 mm, which meets the requirements of the specifications. Overall, the seismic performance of the seismic isolation structure is good, and the isolation scheme is feasible.

Impacts of Waste Rubber Products on the Structure and Properties of Modified Asphalt Binder: Part II-Rubber Reclaim.

The issue of forming a reliable and stable structure of a crumb-rubber-modified binder is an important scientific and technical task. The authors supplemented existing concepts of the mechanism of effective interaction with rubber crumb by introducing a preliminary first stage: controlled partial physical destruction of rubber crumb-producing rubber reclaim. Proposed physical methods of rubber crumb destruction include high shear force (roll mills), high temperature, and a plasticizing medium. The controllability and degree of devulcanization of rubber were determined by acetone-chloroform extraction in different time intervals. The degree of devulcanization of rubber in the rubber reclaim was found to be 22 ± 0.24%, with stability over 14 days. It was found that the size of the particles of the rubber reclaim in the bitumen is less than 2 µm. The properties of the structure of the binder modified with rubber reclaim, characterizing the stability and sustainability, have been studied and established. The developed modified binders are stable in storage. Rheological parameters of the structure characterizing intermolecular interaction, such as shear stability for original and RTFOT-aged, modified bitumen, meet requirements of the state standard at test temperature 64 °C. The elastic structural component of the crumb-rubber-modified binder, as indicated by the relative irreversible deformation parameter J3,2, does not exceed 2.6 kPa (<4.5 kPa) at 64 °C. Additionally, it was determined that the rheological structural parameter for fatigue resistance, which characterizes the durability of road pavement under intensive operational conditions, does not exceed 4699 kPa (<5000 kPa) at 16 °C. The use of 10% rubber reclaim combined with waste frying oil provided the opportunity to obtain a modified binder with a stable and sustainable structure without the introduction of additional stabilizers and agents. Test results showed that the overall performance characteristics of the modified binder meet the 64(S)-40 grade standards.

Numerical analysis of FRP retrofitting in RC beam-column exterior joints at high temperatures and predictive modeling using artificial neural networks

PurposeThe purpose of this study is to perform a numerical analysis of fiber-reinforced polymer (FRP) retrofitting in reinforced concrete (RC) joints at high temperatures and predict models using artificial neural networks (ANN). The aim was to gain insights into their structural behavior across a range of loading conditions from room temperature to 800°C. Additionally, the research assessed the efficiency of carbon fiber-reinforced polymer (CFRP), glass fiber reinforced polymer (GFRP) and aramid fiber reinforced polymer (AFRP) strengthening in enhancing the structural performance of the critical sections.Design/methodology/approachThe linear numerical simulations were conducted to evaluate the performance of RC beam-column joints using finite element modelling (FEM) analysis. The ANN model demonstrated exceptional effectiveness in predicting the stiffness of frames with openings, establishing itself as the premier machine learning algorithm for frame stiffness estimation. In the conventional model, 300°C was proven to be an effective temperature approach. Subsequently, maintaining a constant temperature of 300°C, an in-depth analysis of nearly 30 models of three retrofitting techniques was conducted under thermomechanical loading.FindingsThe CFRP retrofits yielded 15% less deflection and 30% more stress than the remaining FRPs, and the ANN models predicted the deflection, main stresses, bending moment and shear force. The ANN model results were compared with those of other frequently used models. The R thresholds (R = 0.954, 0.981, 0.986, 0.968, 0.978 and 0.936) for training, testing and validation indicated that the ANN model achieved data variability. The findings indicate that the ANN model is more accurate because of the strong connection between the numerical model and the prediction.Originality/valueTo identify the pinpoint of critical segments within the rehabilitation section and determine the most effective wrapping method among the three laminates.

Towards Autonomous Retail Stocking and Picking: Methods Enabling Robust Vacuum-Based Robotic Manipulation in Densely Packed Environments.

With the advent of robotics and artificial intelligence, the potential for automating tasks within human-centric environments has increased significantly. This is particularly relevant in the retail sector where the demand for efficient operations and the shortage of labor drive the need for rapid advancements in robot-based technologies. Densely packed retail shelves pose unique challenges for robotic manipulation and detection due to limited space and diverse object shapes. Vacuum-based grasping technologies offer a promising solution but face challenges with object shape adaptability. The study proposes a framework for robotic grasping in retail environments, an adaptive vacuum-based grasping solution, and a new evaluation metric-termed grasp shear force resilience-for measuring the effectiveness and stability of the grasp during manipulation. The metric provides insights into how retail objects behave under different manipulation scenarios, allowing for better assessment and optimization of robotic grasping performance. The study's findings demonstrate the adaptive suction cups' ability to successfully handle a wide range of object shapes and sizes, which, in some cases, overcome commercially available solutions, particularly in adaptability. Additionally, the grasp shear force resilience metric highlights the effects of the manipulation process, such as in shear force and shake, on the manipulated object. This offers insights into its interaction with different vacuum cup grasping solutions in retail picking and restocking scenarios.

Decoding roughness perception in distributed haptic devices

Abstract The ability to render realistic texture perception using haptic devices has been consistently challenging. A key component of texture perception is roughness. When we touch surfaces, mechanoreceptors present under the skin are activated and the information is processed by the nervous system, enabling perception of roughness/smoothness. Several distributed haptic devices capable of producing localized skin stretch have been developed with the aim of rendering realistic roughness perception; however, current state-of-the-art devices rely on device fabrication and psychophysical experimentation to determine whether a device configuration will perform as desired. Predictive models can elucidate physical mechanisms, providing insight and a more effective design iteration process. Since existing models (1, 2) are derived from responses to normal stimuli only, they cannot predict the performance of laterally actuated devices which rely on frictional shear forces to produce localized skin stretch. They are also unable to predict the augmentation of roughness perception when the actuators are spatially dispersed across the contact patch or actuated with a relative phase difference (3). In this study, we have developed a model that can predict the perceived roughness for arbitrary external stimuli and validated it against psychophysical experimental results from different haptic devices reported in literature. The model elucidates two key mechanisms: 1) The variation in the change of strain across the contact patch can predict roughness perception with strong correlation 2) The inclusion of lateral shear forces is essential to correctly predict roughness perception. Using the model can accelerate device optimization by obviating the reliance on trial-and-error approaches.

Infiltration Characteristics and Hydrodynamic Parameters in Response to Topographic Factors in Bare Soil Surfaces, Laboratory Experiments Based on Cropland Fields of Purple Soil in Southwest China

Topography is an important factor that impacts the hydrological processes on sloping farmlands. Yet, few studies have reported the combined influences of slope gradient and slope position on infiltration characteristics and hydrodynamic parameters on sloping croplands in purple soil regions, an important area for agricultural productivity in Southwest China. Here, laboratory-simulated rainfall experiments were conducted in a steel trough (5 m long, 2 m wide, and 0.45 m deep), and rainfall lasted for 1 h at a rate of 90 mm h−1 to examine the variations in the infiltration rates and hydrodynamic parameters under varying slope gradients (i.e., 3°, 6°, 10°, 15°, 21°, and 27°) and slope positions (i.e., upper, middle, and lower), and explore the relationships between the infiltration rate and the soil detachment rate. The results showed that the infiltration rate decreased gradually with duration rainfall and ultimately approached a steady state in the six slope treatments. Cumulative infiltration ranged from 15.54 to 39.32 mm during rainfall, and gradually reduced with the increase of slope gradient. The Horton’s model outperforms other models for predicting the infiltration rate with an R2 value of 0.86. Factors such as Darcy–Weisbach friction, flow shear force, Manning friction coefficient, unit energy, and runoff depth varied in the following order: upper slope &gt; middle slope &gt; lower slope, whilst the Reynolds number and Froude number gradually increased along the slope transect from the upper to lower slope positions. A significant linear function was fitted between the soil detachment rate and the infiltration rate at the gentle slopes (3°, 6°, 10°), whereas an exponential relationship was observed at the steep slopes (15°, 21°, and 27°). Observation also suggested that 15° was the critical slope gradient of sediment detachment, infiltration characteristics, and hydrodynamic parameters. Our results provide theoretical insight for developing models that predict the impacts of topographic factors on hydrological characteristic and soil erosion in hilly agricultural landscapes of purple soil fields.

Dynamic response of pile–slab retaining wall structure under rockfall impact

Abstract. Pile–slab retaining walls, as innovative rockfall protection structures, have been extensively utilized in the western mountainous regions of China. With their characteristics of a small footprint, high interception height, and ease of construction, these structures demonstrate promising potential for application in mountainous regions worldwide, such as the Himalayas, Andes, and Alps. However, their dynamic response upon impact and impact resistance energy remain ambiguous due to the intricate composite nature of the structures. To elucidate this, an exhaustive dynamic analysis of a four-span pile–slab retaining wall with a cantilever section of 6 m under various impact scenarios was conducted utilizing the finite-element numerical simulation method. The rationality of the selected material constitutive models and the numerical algorithm was validated by reproducing two physical model tests. The simulation results reveal the following. (1) The lateral displacement of the pile at the ground surface and the concrete damage under the pile at the impact center are greater than those under the slab at the impact center, implying that the impact location has a significant influence on the stability of the structure. (2) There is a positive correlation between the response indexes (impact force, interaction force, lateral deformation of pile and slab, concrete damage) and the impact velocities. (3) The rockfall peak impact force, the ratio of the peak impact force to the peak interaction force, and lateral displacement of the pile at the ground surface had strong linear relationships with rockfall energy. (4) Relative to the bending moment, shear force, and damage degree, the lateral displacement of the pile at the ground surface is the first to reach its limit value. Taking the lateral displacement of the pile at the ground surface as the controlling factor, the estimated maximum impact energy that the pile–slab retaining wall can withstand is 905 kJ in this study when the structure top is taken as the impact point. In cases where the impact energy of falling rocks exceeds 905 kJ, it is recommended to optimize the mechanical properties of the cushion layer, improve the elastic modulus of concrete, increase the reinforcement ratio of longitudinal tension bars, enlarge the section size of piles at ground level, or add anchoring measures to enhance the bending resistance of the retaining structure.

Changes in Texture and Collagen Properties of Pork Skin during Salt-Enzyme-Alkali Tenderization Treatment.

The effects of salt-enzyme-alkali progressive tenderization treatments on porcine cortical conformation and collagen properties were investigated, and their effectiveness and mechanisms were analyzed. The tenderization treatment comprised three treatment stages: CaCl2 (25 °C/0-30 min), papain (35 °C/30-78 min), and Na2CO3 (25 °C/78-120 min). The textural, microscopic, and collagenous properties (content, solubility, and structure) of pork skin were determined at the 0th, 30th, 60th, 90th, and 120th min of the treatment process. The results showed that the shear force, hardness, and chewability of the skin decreased significantly (p < 0.05), and the elasticity exhibited a gradual increase with the progression of tenderization. The content and solubility of collagen showed no significant change at the CaCl2 treatment stage. However, the soluble collagen content increased, the insoluble collagen content decreased, and the collagen solubility increased by 18.04% during the subsequent treatment with papain and Na2CO3. Meanwhile, the scanning electron microscopy results revealed that the regular, wavy structure of the pig skin collagen fibers gradually disappeared during the CaCl2 treatment stage, the overall structure revealed expansion, and the surface microscopic pores gradually increased during the papain and Na2CO3 treatment stages. The findings of the Fourier transform infrared spectroscopy analysis indicated that the hydrogen bonding interactions between the collagen molecules and the C=O, N-H and C-N bonds in the subunit structure of collagen were substantially altered during treatment and that the breakage of amino acid chains and reduction in structural ordering became more pronounced with prolonged treatment. In the tertiary structure, the maximum emission wavelength was blue-shifted and then red-shifted, and the fluorescence intensity was gradually weakened. The surface hydrophobicity was slowly increased. The salt-enzyme-alkali tenderization treatment considerably improved the physical properties and texture of edible pork skins by dissolving collagen fibers and destroying the structure of collagen and its interaction force.