Experimental and CFD analysis of fluid flow through nanofiber filter media.

This work presents a novel approach to investigating the slip effect in nanofiber filter media. Electrospun nanofiber media with high efficiency and low pressure drop were produced at different concentrations and durations. The surface and cross-sectional morphology of nanofiber media were studied using FE-SEM. Fiber orientation and diameter distributions were also examined. The 3D virtual nanofiber media was modeled using this information along with the experimentally measured porosity and thickness of the media. The effect of the slip phenomenon in nanofiber media was studied numerically, and the results were compared to experimental data. Excellent agreements were found between the measured and simulation results. Additionally, filtration simulations considering aerosols injected with airflow through the nanofibrous filter media were conducted by considering the slip effect, and the effect of filter structure on filtration performance (removal efficiency and pressure drop) was investigated.

Design, Fabrication, and Validation of a Portable Perturbation Treadmill for Balance Recovery Research.

Trips and falls are a major concern for older adults. The resulting injury and loss of mobility can have a significant impact on quality of life. An emerging field of study, known as Perturbation Training, has been shown to reduce injury rates associated with trips and falls in older adults. Treadmills traditionally used for Perturbation Training are large, expensive, and immobile, forcing users to travel long distances to receive care. A portable treadmill would serve a larger portion of the at-risk population than current methods. We developed a portable, low-cost, twin-belt perturbation treadmill capable of high-intensity Perturbation Training. Belt speeds are controlled by a custom mechanical and software interface, allowing operators with no programming experience to control the device. The treadmill can accommodate users up to 118 kg and provides a maximum acceleration and speed of 12 m/s2 and 3.3 m/s, respectively, under full load. The total weight is 180 kg, and the treadmill can be moved like a wheelbarrow, with handles in the back and wheels in the front. The prototype was validated with mechanical and human participant testing, showing it as a viable device for Perturbation Training. In this paper, we will go over the design, fabrication, and validation processes used to create the Portable Perturbation Treadmill.

Central slip defect reconstruction utilizing partial ulnar side of flexor digitorum superficial tendon for chronic boutonniere deformity: A case report.

Background: Post-traumatic central slip injuries, resulting in boutonniere deformity, are a complex issue that can significantly impact hand function and quality of life. The deformity should be easily reducible in the acute phase, but if left untreated, it shortens the oblique retinacular ligament, leading to chronic contracture. This is a challenging issue in hand surgery, as chronic central slip defects cannot be sutured like other tendon. Various methods for reconstructing central slips have been discussed, but the best method for subacute or chronic injuries remains unclear. This case presents a case of chronic traumatic boutonniere deformity with central slip defect reconstruction. Case report: A 65-year-old male patient presented with swelling and boutonniere deformity on the digiti III of the right hand. The patient had previously fallen from a motorcycle, and the patient's right middle finger got was by a motorcycle six months ago. After the incident, the patient's right middle finger cannot be fully extended. The patient's right hand showed edema with flexion of the interphalangeal (PIP) joint and hyperextension of the distal interphalangeal (DIP) joint. The Range of Motion (ROM) of the PIP joint right middle finger was 45-110 degrees. The X-ray of the right hand AP/oblique showed no bone involvement in the deformity. The patient underwent central slip defect reconstruction utilizing the partial ulnar side of the flexor digitorum superficial tendon. A PIP joint extension splint was applied for 2 weeks. Active and passive exercise of the ROM of the PIP joint began after 2 weeks of PIP extension joint splinting. The patient's ROM of the PIP joint (0-90 degrees) significantly improved 1 month after surgery. The patient's ROM of the PIP joint returned to normal after 2 months after surgery. The function of the patient's right hand is evaluated with the DASH score, which improves significantly from 50 to 4.2. Conclusion: Central slip defect reconstruction utilizing the partial ulnar side of the flexor digitorum superficial tendon is a reliable method for traumatic chronic boutonniere deformity and results in great functional outcomes after 2 months of follow-up. Central slip defect reconstruction utilizing the partial ulnar side of the flexor digitorum superficial tendon is a simple and cost-effective method compared to other methods.

Unique stick-slip crack dynamics of double-network hydrogels under pure-shear loading.

In this work, we have found that a prenotched double-network (DN) hydrogel, when subjected to tensile loading in a pure-shear geometry, exhibits intriguing stick-slip crack dynamics. These dynamics synchronize with the oscillation of the damage (yielding) zone at the crack tip. Through manipulation of the loading rate and the predamage level of the brittle network in DN gels, we have clarified that this phenomenon stems from the significant amount of energy dissipation required to form the damage zone at the crack tip, as well as a kinetic contrast between the rapid crack extension through the yielding zone (slip process) and the slow formation of a new yielding zone controlled by the external loading rate (stick process).

Quasi-Reaction Coarse-Grained Simulation: Unveiling the Mesoscale Interfacial Response of CSH/PVA Fiber.

The lack of a comprehensive force field and understanding at the mesoscale for hydrated calcium silicate (CSH)/polyvinyl alcohol (PVA) fiber has hindered the upscaling and bridging of nanoscale to macroscale phenomena. In this study, we propose a coarse-grained (CG) force field that incorporates bond-breaking operations to endow fiber reactivity, abrasion, and fracture properties. By employing a cubic lattice modeling, we effectively address the challenges associated with semicrystalline relaxation of fibers. For the first time, quasi-reaction CG simulation successfully replicates slip-hardening behaviors and surface abrasion. We demonstrate that abrasion improves interface load transfer and triggers slip-hardening by redistributing stress. Additionally, the influences of single and coupled factors, such as nonbonding interactions and surface roughness, are investigated. Mesoscale understanding provides insights for enabling precise control of load transfer paths and fabrication of interface damage-predictable materials.

Pedestrian wintertime slip and fall injuries-effectiveness of weather warning service in prevention.

BACKGROUND AND AIM: In climates with wintry conditions, slip and fall injuries of pedestrians during wintertime can result in high healthcare and societal costs. The aim of this study was to evaluate the effectiveness of early warnings about slipperiness in preventing such injuries in Finland. Since 2004, the Finnish Meteorological Institute (FMI) has been providing a weather service for pedestrians, which has been developed continuously over time. DATA AND METHODS: Time series of pedestrian slip and fall injuries in commuting on foot in the 19 regions of Finland in 2005-2022 was obtained from the Finnish Workers' Compensation Center and analysed for trends. We also analysed daily warnings about slippery sidewalks from the FMI archives for the period 2011-2022. To identify steps in the service chain that require improvement, we conducted a weather service chain analysis (WSCA) based on a slip and fall accident storyline. RESULTS: There was no significant trend in the number of slipping injuries during the study period. The exposure of the Finnish population to slippery conditions varies according to the climate of the region and characteristics of the winters. We found that the responses of the users of the warning information may be inadequate. CONCLUSIONS: Changes in the behaviour of individuals and more efficient winter maintenance of sidewalks are required. Furthermore, it is necessary to promote the role and safety of walking in the planning of traffic systems and urban planning. Further improvements to the pedestrian weather service are needed as well.

Investigation on dynamic mechanism of fault slip and casing deformation during multi-fracturing in shale gas wells.

Fracturing horizontal well casing deformation has become very prominent, particularly in tectonic stress-concentrated shale gas fields, limiting the efficient development progress of shale gas. The main failure mode of casing shearing deformation had been attributed to fault slip caused by multi-fracturing. The current research did not provide a clear picture of the dynamic evolution relationship between hydraulic fracturing, fault slip, and casing deformation. In this paper, the dynamic model of fault slip induced by formation pressure change is established, incorporating the effects of stress drop, physical change of friction, and casing and cement-sheath resistance loads. The discontinuous displacement approach and explicit/implicit coupling iteration methods are used to reveal the relationships between the effective normal stress, shear stress, friction coefficient, and sliding velocity during the fault slip process. Furthermore, the microscopic process of casing deformation sheared by fault slip is investigated using static equilibrium theory, and a characterization method for determining the amount casing deformation caused by real-scale fault slip is proposed. The results show that three stages exist in the process of casing deformation sheared by fault slip, including trigger activation stage, accelerated slip stage, and deceleration slip stage. Fault slip is clearly influenced by fault strike. To reduce the amount of fault slip, the fault direction with the maximum in-situ stress should be avoided as much as possible. Serious casing deformation still occurs for large-scale activated faults even though the optimization measure of wellbore structure has been well taken. To fundamentally reduce the possibility of casing shear deformation, it is necessary to prevent fault slip through optimizing the design of hydraulic fracturing. This study lays the theoretical groundwork for the casing deformation control method in shale gas wells.

Successful detection of multiple communicating holes in multiple spinal extradural arachnoid cysts by using time-spatial labeling inversion pulse magnetic resonance imaging: illustrative case.

BACKGROUND: Spinal extradural arachnoid cysts (SEACs) communicate with the subarachnoid space through small communicating dural holes. The precise preoperative detection of all communicating holes, followed by minimally invasive dural closure, is the ideal treatment to prevent postoperative spinal deformities, especially in cases of multiple SEACs. However, standard imaging methods often fail to detect communicating hole locations. Although a few cases of successful single-hole detection via cinematic magnetic resonance imaging (MRI) have been reported, this modality's ability to detect multiple holes has not been demonstrated. OBSERVATIONS: The authors describe the case of a 14-year-old male with myelopathy due to multiple SEACs at T5-8 and T8-12. Myelography revealed a complete block at the T8 level; no cephalic cyst or communicating holes were identified. Time-spatial labeling inversion pulse (T-SLIP) MRI revealed cerebrospinal fluid flow into the cyst at T10 and T7. A limited laminectomy or hemilaminectomy was performed at T7 and T10, and two dural holes were closed without a total cystectomy. The patient's gait disturbance and rectal disorder disappeared. The cysts were confirmed to have completely disappeared on conventional MRI at 1 year postoperatively. LESSONS: T-SLIP MRI, a cinematic MRI, is useful for detecting multiple communicating holes in SEACs.

Effects of reservoir mechanical properties on induced seismicity during subsurface hydrogen storage.

The intermittent storage of hydrogen in subsurface porous media such as depleted gas fields could be pivotal to a successful energy transition. Numerical simulations investigate the intermittent storage of hydrogen in a porous, depleted subsurface reservoir. Various parametric studies are performed to assess the effect of mechanical properties of the reservoir (i.e. Young's modulus, Poisson's ratio, Biot coefficient and permeability) on the induced fault slip of a single through-going fault that transverses the entire reservoir. Simulations are run using a three-dimensional, finite element, fully coupled hydromechanical code with explicit representations of layers and faults. The effect of the domain mesh refinement and fault mesh refinement on the fault slip versus operation time solution is investigated. The fault is observed to slip in two distinct events, one during the second injection period and one in the third injection period. The fault is not observed to slip during the storage or withdrawal periods. It is found that in order to minimize seismic risk, a reservoir rock with high Young's modulus (>40 GPa), high Poisson's ratio (>0.30) and high Biot coefficient (>0.65) would be preferable for hydrogen storage. Reservoir rocks of low Young's modulus (10-30 GPa), intermediate Poisson's ratio (0.00-0.30) and low-to-intermediate Biot coefficient (0.25-0.65), at high injection rates, were found to have higher potential of inducing large seismic events.This article is part of the theme issue 'Induced seismicity in coupled subsurface systems'.

Fluid-driven aseismic fault slip with permeability enhancement and dilatancy.

Injection-induced seismicity and aseismic slip often involve the reactivation of long-dormant faults, which may have extremely low permeability prior to slip. In contrast, most previous models of fluid-driven aseismic slip have assumed linear pressure diffusion in a fault zone of constant permeability and porosity. Slip occurs within a frictional shear crack whose edge can either lag or lead pressure diffusion, depending on the dimensionless stress-injection parameter that quantifies the prestress and injection conditions. Here, we extend this foundational work by accounting for permeability enhancement and dilatancy, assumed to occur instantaneously upon the onset of slip. The fault zone ahead of the crack is assumed to be impermeable, so fluid flow and pressure diffusion are confined to the interior, slipped part of the crack. The confinement of flow increases the pressurization rate and reduction of fault strength, facilitating crack growth even for severely understressed faults. Suctions from dilatancy slow crack growth, preventing propagation beyond the hydraulic diffusion length. Our new two-dimensional and three-dimensional solutions can facilitate the interpretation of induced seismicity data sets. They are especially relevant for faults in initially low permeability formations, such as shale layers serving as caprock seals for geologic carbon storage, or for hydraulic stimulation of geothermal reservoirs.This article is part of the theme issue 'Induced seismicity in coupled subsurface systems'.

Strong-Yet-Ductile Eutectic Alloys Employing Cocoon-Like Nanometer-Sized Dislocation Cells.

Eutectic alloys (EAs) with superior fluidity are known to be the easiest to cast into high-quality ingots, making them the alloys of choice for making large-sized structural parts. However, conventional EAs (CEAs) have never reached strength-ductility combinations on par with the best in other alloy categories. Via thermomechanical processing of cast Ni-32.88wt%Fe-9.53wt%Al CEAs, a cocoon-like nano-meshed (as fine as 26 nm) network of dislocations (CNN-D) is produced via recovery annealing, through the rearrangement of cold-work-accumulated dislocations anchored by dense pre-existing nanoprecipitates. In lieu of traditional plasticity mechanisms, such as TWIP and TRIP, the CNN-D is particularly effective in eutectic lamellae with alternating phases, as it instigates nanometer-spaced planar slip bands that not only dynamically refine the microstructure but also transmit from the FCC (face-centered-cubic) layers into the otherwise brittle B2 layers. These additional mechanisms for strengthening and strain hardening sustain stable tensile flow, resulting in a striking elevation of both strength and ductility to outrank not only all previous CEAs, but also the state of the art-additively manufactured eutectic high-entropy alloys. The CNN-D thus adds a novel microstructural strategy for performance enhancement, especially for compositionally complex alloys that increasingly make use of nanoprecipitates or local chemical order.

Study on TPD Phasemeter to Suppress Low-Frequency Amplitude Fluctuation and Improve Fast-Acquiring Range for GW Detection.

A phasemeter as a readout system for the inter-satellite laser interferometer in a space-borne gravitational wave detector requires not only high accuracy but also insensitivity to amplitude fluctuations and a large fast-acquiring range. The traditional sinusoidal characteristic phase detector (SPD) phasemeter has the advantages of a simple structure and easy realization. However, the output of an SPD is coupled to the amplitude of the input signal and has only a limited phase-detection range due to the boundedness of the sinusoidal function. This leads to the performance deterioration of amplitude noise suppression, fast-acquiring range, and loop stability. To overcome the above shortcomings, we propose a phasemeter based on a tangent phase detector (TPD). The characteristics of the SPD and TPD phasemeters are theoretically analyzed, and a fixed-point simulation is further carried out for verification. The simulation results show that the TPD phasemeter tracks the phase information well and, at the same time, suppresses the amplitude fluctuation to the noise floor of 1 µrad/Hz1/2, which meets the requirements of GW detection. In addition, the maximum lockable step frequency of the TPD phasemeter is almost three times larger than the SPD phasemeter, indicating a greater fast-acquiring range.

Effect of Weight Distribution and Active Safety Systems on Electric Vehicle Performance.

This paper describes control methods to improve electric vehicle performance in terms of handling, stability and cornering by adjusting the weight distribution and implementing control systems (e.g., wheel slip control, and yaw rate control). The vehicle is first simulated using the bicycle model to capture the dynamics. Then, a study on the effect of weight distribution on the driving behavior is conducted. The study is performed for three different weight configurations. Moreover, a yaw rate controller and a wheel slip controller are designed and implemented to improve the vehicle's performance for cornering and longitudinal motion under the different loading conditions. The simulation through the bicycle model is compared to the experiments conducted on a rear-wheel driven radio-controlled (RC) electric vehicle. The paper shows how the wheel slip controller contributes to the stabilization of the vehicle, how the yaw rate controller reduces understeering, and how the location of the center of gravity (CoG) affects steering behavior. Lastly, an analysis of the combination of control systems for each weight transfer is conducted to determine the configuration with the highest performance regarding acceleration time, braking distance, and steering behavior.

Source Models of the 2016 and 2022 Menyuan Earthquakes and Their Tectonic Implications Revealed by InSAR.

The Haiyuan fault system plays a crucial role in accommodating the eastward expansion of the Tibetan Plateau (TP) and is currently slipping at a rate of several centimeters per year. However, limited seismic activities have been observed using geodetic techniques in this area, impeding the comprehensive investigation into regional tectonics. In this study, the geometric structure and source models of the 2022 Mw 6.7 and the 2016 Mw 5.9 Menyuan earthquakes were investigated using Sentinel-1A SAR images. By implementing an atmospheric error correction method, the signal-to-noise ratio of the 2016 interferometric synthetic aperture radar (InSAR) coseismic deformation field was significantly improved, enabling InSAR observations with higher accuracy. The results showed that the reliability of the source models for those events was improved following the reduction in observation errors. The Coulomb stress resulting from the 2016 event may have promoted the strike-slip movement of the western segment of the Lenglongling fault zone, potentially expediting the occurrence of the 2022 earthquake. The coseismic slip distribution and the spatial distribution of aftershocks of the 2022 event suggested that the seismogenic fault may connect the western segment of the Lenglongling fault (LLLF) and the eastern segment of the Tuolaishan fault (TLSF). Additionally, the western segment of the surface rupture zone of the northern branch may terminate in the secondary branch close to the Sunan-Qilian fault (SN-QL) strike direction, and the earthquake may have triggered deep aftershocks and accelerated stress release within the deep seismogenic fault.

Evaporation Dynamics on a Lithium Niobate Surface.

Manipulating water evaporation dynamics is a prerequisite in various modern-day applications like DNA stretching, rapid disease diagnostics, and inkjet printing. One method to affect the evaporation dynamics of droplets is to externally apply electric fields. However, surfaces that bear an intrinsic surface charge have not yet been investigated with respect to their evaporation behavior. In this study, we investigate water droplet evaporation on lithium niobate (LN), a ferroelectric material with a very high spontaneous polarization of 0.7 C/m2. Our results show that a droplet deposited on a LN surface evaporates in three stages: (i) constant contact radius (ii) mixed phase (iii) stick-slip, which is likely originating from the intrinsic surface charge. The influences of the polarization direction of the LN surface as well as the relative humidity of the environment on various evaporation characteristics were studied. The results suggest that the specific adsorption layers forming on charged surfaces, e.g. from the humidity of the surrounding air, play a key role in the evaporation process. Furthermore, compared to other materials with similar contact angles, LN demonstrated a significantly large evaporation rate. This property might also be attributed to the intrinsic surface charge and could be exploited in heat transfer applications.

Design of Bionic Foot Inspired by the Anti-Slip Cushioning Mechanism of Yak Feet.

In recent years, legged robots have been more and more widely used on non-structured terrain, and their foot structure has an important impact on the robot's motion performance and stability. The structural characteristics of the yak foot sole with a high outer edge and low middle, which has excellent soil fixation ability and is an excellent bionic prototype, can improve the friction between the foot and the ground. At the same time, the foot hooves can effectively alleviate the larger impact load when contacting with the ground, which is an excellent anti-slip buffer mechanism. The bionic foot end design was carried out based on the morphology of the yak sole; the bionic foot design was carried out based on the biological anatomy observation of yak foot skeletal muscles. The virtual models of the bionic foot end and the bionic foot were established and simulated using Solidworks 2022 and Abaqus 2023, and the anti-slip performance on different ground surfaces and the influence of each parameter of the bionic foot on the cushioning effect were investigated. The results show that (1) the curved shape of the yak sole has a good anti-slip performance on both soil ground and rocky ground, and the anti-slip performance is better on soil ground; (2) the curved shape of the yak sole has a larger maximum static friction than the traditional foot, and the anti-slip performance is stronger under the same pressure conditions; (3) the finger pillow-hoof ball structure of the bionic foot has the greatest influence on the buffering effect, and the buffering effect of the bionic foot is best when the tip of the bionic foot touches the ground first.

Translating proof-of-concept for platelet slip into improved antithrombotic therapeutic regimens.

Platelets are central to thrombosis. Research at the intersection of biological and physical sciences provides proof-of-concept for shear rate-dependent platelet slip at vascular stenosis and near device surfaces. Platelet slip extends the observed biological "slip-bonds" to the boundary of functional gliding without contact. As a result, there is diminished engagement of the coagulation cascade by platelets at these surfaces. Comprehending platelet slip would more precisely direct antithrombotic regimens for different shear environments, including for percutaneous coronary intervention (PCI). In this brief report we promote translation of the proof-of-concept for platelet slip into improved antithrombotic regimens by: (1) reviewing new supporting basic biological science and clinical research for platelet slip; (2) hypothesizing the principal variables that affect platelet slip; (3) applying the consequent construct model in support of-and in some cases to challenge-relevant contemporary guidelines and their foundations (including for urgent, higher-risk PCI); and (4) suggesting future research pathways (both basic and clinical). Should future research demonstrate, explain and control platelet slip, then a paradigm shift for choosing and recommending antithrombotic regimens based on predicted shear rate should follow. Improved clinical outcomes with decreased complications accompanying this paradigm shift for higher-risk PCI would also result in substantive cost savings.

Temperature-Induced Variations in Slip Behavior of Single Crystal Aluminum: Microstructural Analysis.

The simultaneous increase in strength and plasticity of aluminum and its alloys at cryogenic temperatures has been shown in previous research, but the deformation mechanism was still unclear. Therefore, the purpose of this investigation was to reveal the relationship between slip behavior and mechanical response at low temperatures. A quasi-in situ scanning electron microscope was used to observe the evolution of slip bands in the selected aluminum single crystals with two typical orientations at 25 °C, -100 °C, and -180 °C. The results showed that irrespective of orientation, the density of the slip plane was increased with the decline in temperature, which inhibited slip localization and significantly improved plasticity and work hardening. In detail, at RT, the slip bands were widening until the micro-cracks were generated, causing early failure during deformation. When the temperature was decreased to -180 °C, the slip plane density was increased, and the deformation was more homogenous. Moreover, the slip mode was influenced by orientation and temperature. In particular, a single slip system was activated in the sample with the [112] orientation at all the temperatures investigated. Multiple slip systems were found to activate at 25 °C and -100 °C, and only the primary slip system was activated in the sample with [114] orientation at -180 °C. These findings deepen the understanding of slip behavior at cryogenic temperatures, providing new insights into the deformation mechanism of aluminum and its alloys.

Numerical simulation for MHD Oldroyd-B fluid flow with melting and slip effect.

This investigation reflects an examination of Oldroyd-B fluid flow over a permeable surface subjected to the effects of melting, slip effect, inclined magnetic field and chemical reactions. The governing equations are resolved using the bvp4c inbuilt MATLAB tool, the arithmetic computation for the momentum, thermal and concentration equations are executed. The results are exhibited graphically. Numerical outcomes are graphically depicted by aid of velocity, concentration, temperature profiles for several model variables. The achieved results exhibit a promising agreement with the previously established findings available in the open literature. The results obtained indicated that Deborah number ß 1 reduces the momentum boundary layer thickness whereas Deborah number ß 2 enhances the adjacent momentum boundary layer. Furthermore, temperature profile declined for melting parameter Me . The application of this study transcends various engineering disciplines, offering practical solutions and optimization opportunities in polymer processing, coating technologies, cooling systems, materials processing, biomedical and environmental engineering.

The extent to which healthy older adults rely on anticipatory control following simulated slip exposure.

As the recovery from gait perturbations is coordinatively complex and error-prone, people often adopt anticipatory strategies when the perturbation is expected. These anticipatory strategies act as a first line of defence against potential balance loss. Since age-related changes in the sensory and neuromotor systems could make the recovery from external perturbations more difficult, it is important to understand how older adults implement anticipatory strategies. Therefore, we exposed healthy young (N = 10, 22 ± 1.05 yrs.) and older adults (N = 10, 64.2 ± 6.07 yrs.) to simulated slips on a treadmill with consistent properties and assessed if the reliance on anticipatory control differed between groups. Results showed that for the unperturbed steps in between perturbations, step length decreased and the backward (BW) margin of stability (MOS) increased (i.e., enhanced dynamic stability against backward loss of balance) in the leg that triggered the slip, while step lengths increased and BW MOS decreased in the contralateral leg. This induced step length and BW MOS asymmetry was significantly larger for older adults. When exposed to a series of predictable slips, healthy older adults thus rely more heavily on anticipatory control to proactively accommodate the expected backward loss of balance.