Soft Stiffness Research Articles

Numerical Study on Soil‐Arching Behavior in Pile‐Supported Embankments With Pile Settlement by Developed Damping Spring‐Based Trapdoor Model

ABSTRACTSoil arching is one of the main mechanisms for load transfer in pile‐supported embankments, and the soil arching evolution patterns varied significantly depending on fill heights, pile spacings, pile stiffness, and soil stiffness. However, research on the effect of pile settlement on soil arching is relatively scarce, and most studies still use the traditional trapdoor test with a fixed arch foot to examine the soil arching. Therefore, this study establishes numerical models of a damping spring‐based trapdoor that considers pile settlement, and through 52 sets of spring‐based trapdoor tests and 1 set of reference tests, it systematically investigates the effects of various factors such as pile–soil stiffness ratio, fill height, and pile spacing on the soil arching under pile settlement conditions. The research results show that reducing the pile–soil stiffness ratio will reduce differential settlement between piles and soil, but it will exacerbate overall settlement. The stiffness ratio has a significant impact on soil arching: appropriately reducing the pile–soil stiffness ratio will help to recover fill deformation and suppress the formation of passive soil arch; increasing the stiffness ratio will enhance the stability of the soil arching. In addition, when the soft soil stiffness ks is low, pile settlement helps to enhance the soil arching, and the enhancement effect becomes more significant with an increase in fill height H and pile spacing S/a. When ks is high, pile settlement weakens the soil arching, which intensifies with an increase in fill height but weakens with an increase in S/a.

Substrate stiffness regulates the proliferation and inflammation of chondrocytes and macrophages through exosomes.

Osteoarthritis (OA) progression is characterized by decreased cartilage stiffness and degradation of the extracellular matrix (ECM), which significantly influence cartilage behavior and fate. In contrast, processes such as chondrocyte calcification and aging often result in increased stiffness. Despite extensive studies on how ECM stiffness regulates cellular functions, the impact of substrate stiffness on the cartilage microenvironment and intercellular communications remains not well understood. Using tunable stiffness Gelatin methacryloyl (GelMA) hydrogel, we demonstrated that a potential optimal substrate stiffness can promote maximal chondrocyte proliferation and exosome secretion. The exogenous addition of stiffness-tuned exosomes induced significant changes in chondrocyte morphology, proliferation, migration, and inflammation. Notably, blocking Yes-associated protein (YAP) synthesis negated the proliferation enhancement induced by exosomes from chondrocytes cultured on medium stiffness substrates (ExoMedium), confirming that substrate stiffness regulates cell proliferation through exosomes by modulating YAP expression and its nuclear localization. Moreover, our study revealed that exosomes from medium stiffness substrates-mimicking normal cartilage stiffness-not only reduce inflammation in chondrocytes but also shift macrophage polarization from M1 to M2. Conversely, exosomes from soft stiffness substrates, akin to osteoarthritic tissue, exacerbate chondrocytes inflammation and M1 macrophage polarization. These findings highlight the crucial role of stiffness-tuned exosomes in OA progressing, affecting chondrocyte proliferation, migration, inflammation and macrophage polarization, and provide new insights into the potential novel treatment strategies using engineered scaffolds and exosomes. STATEMENT OF SIGNIFICANCE: Osteoarthritis (OA) is a prevalent degenerative joint disease characterized by decreased cartilage stiffness and degradation of the extracellular matrix (ECM). While some studies suggest that increased substrate stiffness enhances cell proliferation, others have reported the opposite effect. Whether there exists an optimal matrix stiffness that promotes chondrocytes anabolism and how matrix stiffness regulates the cartilage microenvironment and intercellular communications remain unclear. Utilizing tunable stiffness Gelatin methacryloyl (GelMA) hydrogel, this study demonstrated that a potential optimal substrate stiffness can maximize chondrocyte proliferation and exosome secretion. The introduction of stiffness-tuned exosomes induced significant changes in chondrocyte and macrophage proliferation, migration, and inflammation, offering new insights into OA progression and highlighting their potential as a promising therapeutic strategy for osteoarthritis treatment and tissue regeneration.

The interplay between toothbrush stiffness and charcoal-containing dentifrice on the development of enamel topography changes

BackgroundThis study aimed to investigate the in vitro effect of a charcoal-containing dentifrice with different toothbrush stiffness on enamel.MethodsFour main groups were applied: distilled water, conventional fluoridated toothpaste (Colgate® Total® 12 Clean Mint Toothpaste), charcoal toothpaste (Colgate® Total® Charcoal Toothpaste) and whitening toothpaste (Colgate Total® Advanced Whitening Toothpaste). Three subgroups for each toothpaste were further included according to the toothbrush bristles’ stiffness (soft, medium, and hard). Enamel specimens were subjected to 1,250 and 2,500 cycles of brushing using toothbrushing simulation machine. The average surface roughness change (ΔRa) in nanometer (nm) was measured to estimate the changes following the brushing simulation model. Two-way ANOVA and Tukey tests analyzed the data.ResultsThe type of toothpaste and the bristles’ stiffness were determinant factors in increasing the ΔRa value (P = < 0.05). Generally, charcoal and whitening toothpastes with medium and hard bristles yielded higher ΔRa than fluoridated toothpaste and smooth bristles. Following 1,250 cycles of brushing simulation, charcoal toothpaste did not increase the enamel roughness compared to the controls. However, in prolonged brushing via 2,500 cycles of brushing simulation, using bristles with soft stiffness revealed that charcoal toothpaste was associated with increased surface roughness (55.86 ± 41.18 nm), which was statistically significant (P = 0.024) compared to the negative control. Using bristles with medium stiffness showed that the whitening (68.23 ± 48.58 nm) and charcoal (73.62 ± 34.66 nm) toothpastes significantly (P = < 0.05) increased the enamel roughness compared to the conventional toothpaste (36.53 ± 22.56 nm). There was no significant difference among the groups when brushes with hard bristles were used, as all the groups revealed increased enamel roughness.ConclusionThe use of charcoal and whitening toothpastes increased enamel roughness, particularly with long-term use. The effect of bristle stiffness on enamel roughness was found to vary depending on the type of toothpaste used.

Accelerated aspiration with Q™ catheter: An in vitro study.

Thrombectomy in distal, medium vessels is a topic of increasing interest. To date, there are few in vitro studies focused on performance of ≤5F catheters in medium vessels. The purpose of this study is to compare the performance of the 3F, 4F, and 5F MIVI Neuroscience Q Catheters versus Penumbra 3F, 4F, and MicroVention Sofia 5F Catheters. Using in vitro methods, we assessed and compared the following parameters: aspiration flow rates, clot uncorking forces, impulse, and clot ingestion. For flow rate, each aspiration catheter was immersed in a cylindrical container. Flow rate at one second was used to calculate impulse. For clot uncorking force, the force required to disengage a catheter from a simulated clot was recorded. For ingestion, we measured time to ingest soft and medium stiffness synthetic clots. The measured flow rates without a stent retriever for the Q3, Q4, and Q5 catheters were 3.54 ml/s, 5.32 ml/s, and 6.87 ml/s. The measured flow rates without a stent retriever for the 3MAX, 4MAX, and 5F Sofia were 1.46 ml/s, 2.56 ml/s, and 1.73 ml/s. The impulse calculated for one second was 26 mNs for Q5 vs 9 mNs for Sofia 5, 35 mNs for Q4 vs 15 mNs for 4Max< and 35 mNs for Q3 vs 9 mNs for 3Max. The average system ingestion for Q was significantly faster than the competitive catheters. The Q catheters demonstrated higher flow rates, higher uncorking force, and faster complete clot ingestion than competitive catheters.

MyotonPRO as a new valid tool for measuring cervical muscle tension. A reliability study

Objective The main objective of this study is to test the reliability of a non-invasive objective method for the measurement of biomechanical parameters of cervicofacial muscle groups, with the purpose of diagnosis and evaluation of voice disorders’ treatments, especially focused on muscle tension dysphonia. Study design Prospective study. Methods The device used is a handheld myotonometer (MyotonPRO) that measures biomechanical and viscoelastic properties in superficial soft tissues frequency, stiffness, elasticity, relaxation time and creep. It is used in the field of medicine, sport and research. This pilot study includes 10 subjects, who have been measured in the masseter, sternocleidomastoid, orbicularis oris, semispinalis capitis, suprahyoid, infrahyoid and trapezius muscles on each side. Measurements were performed by 2 evaluators to assess inter-evaluator reliability. Subsequently, one of them repeated the measurements to assess intra-evaluator reliability. Results The results revealed good to excellent inter-rater reliability for the masseter, sternocleidomastoid, trapezius and suprahyoid muscles, with lower ICCs for the stiffness and creep properties. Intra-rater reliability was good to excellent for the masseter, sternocleidomastoid, semispinalis capitis and suprahyoid muscles. The lowest ICCs were found in the stiffness and creep properties. Conclusion The use of a myotonometer to measure the mechanical properties of selected cervical and orofacial muscles is a reliable and reproducible method. Future research is needed to establish an association between the properties of these muscles and their role in voice disorders, as well as to determine whether this tool can aid diagnosis with quantifiable and objectifiable indicators, and for monitoring and treatment efficacy.

Matrix stiffness regulates the triad communication of adipocytes/macrophages/endothelial cells through CXCL13

Adipose tissue remodeling and plasticity are dynamically regulated by the coordinated functions of adipocytes, macrophages, and endothelial cells and extracellular matrix (ECM) that provides stiffness networks in adipose tissue component cells. Inflammation and fibrosis are crucial exogenous factors that dysregulate adipose tissue functions and drastically change the mechanical properties of the ECM. Therefore, communication among the ECM and adipose tissue component cells is necessary to understand the multifaceted functions of adipose tissues. To obtain in vivo stiffness, we used genipin as a crosslinker for collagen gels. Meanwhile, we isolated primary adipocytes, macrophages, and endothelial cells from C57BL/6J mice and incubated these cells in the differentiation media on temperature-responsive culture dishes. After the differentiation, these cell sheets were transferred onto genipin-crosslinked collagen gels with varying matrix stiffness. We found that inflammatory gene expressions were induced by hard matrix, whereas antiinflammatory gene expressions were promoted by soft matrix in all three types of cells. Interestingly, the coculture experiments of adipocytes, macrophages, and endothelial cells showed that the effects of soft or hard matrix stiffness stimulation on adipocytes were transmitted to the distant adipose tissue component cells, altering their gene expression profiles under normal matrix conditions. Finally, we identified that a hard matrix induces the secretion of CXCL13 from adipocytes, and CXCL13 is one of the important transmitters for stiffness communication with macrophages and endothelial cells. These findings provide insight into the mechanotransmission into distant cells and the application of stiffness control for chronic inflammation in adipose tissues with metabolic dysregulation.

Soil arching evolution in GRPS embankments: Numerical spring‐based trapdoor tests

AbstractSoil arching is one of the main load transfer mechanisms of geosynthetic‐reinforced and pile‐supported (GRPS) embankments. This study established a numerical spring‐based trapdoor model that can consider the coupling effect between embankment filling, horizontal geosynthetic, piles, and soft soil between piles by the discrete element method (DEM). The effects of multiple factors on the deformation pattern, load transfer, and the settlement at the top surface of GRPS embankments were analyzed, such as soft soil stiffness, geosynthetic stiffness, fill height, and pile clear spacing. The multiple spring‐based trapdoor (MS‐TD) model effectively replicated the actual deformation of soft soil between piles in engineering practice by elucidating the nonuniform settlement of the fill on the trapdoor. Although the geosynthetic indirectly reduces the load transferred to the pile top by weakening the soil arching, it can directly increase the load transferred to the pile top by the membrane effect, thereby increasing the total load transferred to the pile top. The effect of the geosynthetic on reducing settlement decreases with the increase of soft soil stiffness, and the displacement reduction ratio at the top surface remains unchanged when it exceeds a certain value. In addition, the shape of the soil arch evolves rather than unchanged during the growth of pile clear spacing.

ELFN1 is a new extracellular matrix (ECM)-associated protein

AimsThe ELFN1, discovered in 2007, is a single-pass transmembrane protein. Studies conducted thus far to elucidate the function of the Elfn1 have been limited only to animal studies. These studies have reported that ELFN1 is a universal binding partner of metabotropic glutamate receptors (mGluRs) in the central nervous system and its functional deficiency has been associated with the pathogenesis of neurological and neuropsychiatric diseases. In 2021, we described the first disease-associated human ELFN1 pathogenic gene mutation. Severe joint laxity, which was the most striking finding of this new disease and was clearly seen in the patients since early infancy, showed that the ELFN1 may have a possible function in the connective tissue besides the nervous system. Here, we present the first experimental evidence of the extracellular matrix (ECM)-related function of the ELFN1. Materials and methodsPrimary skin fibroblasts were isolated from the skin biopsies of ELFN1 mutated patients and healthy foreskin donors. For the clinical trial in a dish, in vitro ECM and DEM (decellularized ECM) models were created from skin fibroblasts. All the in vitro models were comparatively characterized and analyzed. Key findingsThe mutation in the ELFN1 signal peptide region of patients resulted in a severe lack of ELFN1 expression and dramatically altered the characteristic morphology and behavior (growth, proliferation, and motility) of fibroblasts. SignificanceWe propose that ELFN1 is involved in the cell-ECM attachment, and its deficiency is critical enough to cause a loss of cell motility and soft ECM stiffness.

The dynamic behaviour of flexible oscillators rocking and sliding on concentrated springs

AbstractThis study presents the Flexible Rocking Model on Concentrated Springs (FRMCS), developed to investigate 2D laterally flexible oscillators rocking and sliding on deformable support media during ground excitations. In this model, concentrated vertical springs and viscous dampers simulate the contact forces from support medium at the corners of the body; the tensionless vertical contact element is linear in compression. Horizontal concentrated springs and linear viscous dampers simulate the frictional behaviour at the corners; the constitutive law for the springs models elastic deformations and sliding (according to Coulomb's friction law). With these elements, FRMCS can model the response of a rocking body which can experience sliding and free‐flight phases of motion. The consideration of the flexibility of the support medium enables the evaluation of the forces exerted by the support medium on the structure during an impact. In this study, the FRMCS response is first compared to a previous model where the support medium deformability and the effects of sliding and free‐flight are ignored. Then, the responses of four configurations, which feature either stiff or soft lateral springs and stiff or soft high‐grip support media, are examined under the influence of pulse excitations. Finally, to understand the potential influence of sliding, a configuration with a low‐grip support medium is explored. The comparative influence of lateral flexibility and support medium deformability and sliding is quantified with stability diagrams and various response spectra, describing structural force and moment demands.

Conceptual design and model test of a pontoon-truss type offshore floating photovoltaic system with soft connection

With the growing demand for clean energy in human society, the development of offshore floating photovoltaic (FPV) systems emerged as a prominent research topic. Positive-airgap FPV systems are more practical for engineering applications, however, current designs still face challenges under open sea such as negative airgap risk and significant connecting load. To address these issues, this study presents a novel foundation and connection scheme for an offshore FPV system. First, a pontoon-truss platform was designed and its superior performance was demonstrated by comparing it to a traditional semi-submersible. Further, a four-module offshore FPV system concept was developed, in which soft ropes were first introduced as a solution for FPV module connection. After that, a basin model experiment is employed to evaluate the feasibility of proposed FPV system under wind-wave-current joint effect, where the current-wind load is simplified as a constant force, and the established numerical model is verified by experiments. To improve understanding and design, the impact of several key design parameters on dynamic responses is also discussed. The findings indicate that the airgap performance deteriorates rapidly when single module draught surpasses half of pontoon diameter, and improving soft rope stiffness is more effective and produces less disturbance to other behaviors than enhancing mooring stiffness.

A Soft Variable Stiffness Gripper with Magnetorheological Fluids for Robust and Reliable Grasping

A Soft Variable Stiffness Gripper with Magnetorheological Fluids for Robust and Reliable Grasping

Precision and Test-Retest Repeatability of Stiffness Measurement with MR Elastography: A Multicenter Phantom Study.

Background MR elastography (MRE) has been shown to have excellent performance for noninvasive liver fibrosis staging. However, there is limited knowledge regarding the precision and test-retest repeatability of stiffness measurement with MRE in the multicenter setting. Purpose To determine the precision and test-retest repeatability of stiffness measurement with MRE across multiple centers using the same phantoms. Materials and Methods In this study, three cylindrical phantoms made of polyvinyl chloride gel mimicking different degrees of liver stiffness in humans (phantoms 1-3: soft, medium, and hard stiffness, respectively) were evaluated. Between January 2021 and January 2022, phantoms were circulated between five different centers and scanned with 10 MRE-equipped clinical 1.5-T and 3-T systems from three major vendors, using two-dimensional (2D) gradient-recalled echo (GRE) imaging and/or 2D spin-echo (SE) echo-planar imaging (EPI). Similar MRE acquisition parameters, hardware, and reconstruction algorithms were used at each center. Mean stiffness was measured by a single observer for each phantom and acquisition on a single section. Stiffness measurement precision and same-session test-retest repeatability were assessed using the coefficient of variation (CV) and the repeatability coefficient (RC), respectively. Results The mean precision represented by the CV was 5.8% (95% CI: 3.8, 7.7) for all phantoms and both sequences combined. For all phantoms, 2D GRE achieved a CV of 4.5% (95% CI: 3.3, 5.7) whereas 2D SE EPI achieved a CV of 7.8% (95% CI: 3.1, 12.6). The mean RC of stiffness measurement was 5.8% (95% CI: 3.7, 7.8) for all phantoms and both sequences combined, 4.9% (95% CI: 2.7, 7.0) for 2D GRE, and 7.0% (95% CI: 2.9, 11.2) for 2D SE EPI (all phantoms). Conclusion MRE had excellent in vitro precision and same-session test-retest repeatability in the multicenter setting when similar imaging protocols, hardware, and reconstruction algorithms were used. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Tang in this issue.

STAT3 mediates ECM stiffness-dependent progression in ovarian cancer.

The treatment of ovarian cancer remains a medical challenge and its malignant progression is connected with obvious changes in both tissue and cell stiffness. However, the accurate mechanical-responsive molecules and mechanism remains unclear in ovarian cancer. Based on our previous results combined with the crucial regulatory role of STAT3 in the malignant progression of various cancer types, we want to investigate the relationship between STAT3 and matrix stiffness in ovarian cancer and further explore the potential mechanisms. Collagen-coated polyacrylamide gels (1, 6, and 60 kPa) were prepared to mimic soft or hard matrix stiffness. Western blotting, qRT-PCR, flow cytometry, IHC, EdU assays, and TEM were used to evaluate the effect of STAT3 in vitro under different matrix stiffnesses. Furthermore, a BALB/c nude mouse model was established to assess the relationship in vivo. Our results confirmed the differential expression of STAT3/p-STAT3 not only in normal and malignant ovarian tissues but also under different matrix stiffnesses. Furthermore, we verified that STAT3 was a mechanically responsive gene both in vitro and in vivo, and the mechanical response was carried out by altering the migration-related molecules (TNFAIP1) and adhesion-related molecules (LPXN, CNN3). The novel findings suggest that STAT3, a potential therapeutic target for clinical diagnosis and treatment, is a mechanically responsive gene that responds to matrix stiffness, particularly regulation in migration and adhesion in the progression of ovarian cancer.

Plaque Removal Efficacy of Manual Tooth Brushing in Crowded Mandibular Frontal Teeth

The aim of the present in vivo study was to evaluate the efficacy of two different bristle stiffness, in plaque control of crowded mandibular teeth. To classify the patient mandibular frontal teeth irregularity, the quantitative Little´s Irregularity Index was used. To quantify the dental plaque accumulation, the Distal-Mesial Plaque Index (DMPI) was assessed by a single examiner. After each plaque accumulation period, which lasted for 24 hours, the plaque removal efficacy of a soft or medium stiff manual toothbrush were measured. The mean interproximal DMPI of the irregularity group with mild and moderate crowding was, prior to brushing with the soft bristle toothbrush, 1.87 on the facial surfaces, 1.93 on those of the lingual surfaces, and 1.90 on both the facial and lingual surfaces. The new mean interproximal DMPI after brushing of the facial teeth surfaces was 1.54. On the lingual surfaces an index of 1.58 and on the facial and lingual surfaces combined an index of 1.56 was measured. Considering the percentage of the remaining interdental plaque, on the severely crowded surfaces, the toothbrush with medium bristle stiffness was slightly, with two percent, more effective in removing interproximal plaque with a percentage of 23%, compared to the toothbrush with a soft bristle stiffness removing 21% of the interdental plaque. In conclusion, the manual toothbrush with round-ended medium stiffness bristles was slightly more effective in removing interproximal plaque compared to the toothbrush with round-ended soft bristle stiffness. In comparison, there was a slight difference interdental plaque removal between the soft and medium stiff round-ended toothbrushes, independently of the crowding degree.

Matrix stiffness regulates macrophage polarisation via the Piezo1-YAP signalling axis.

Macrophages play a pivotal role in the immunological cascade activated in response to biomedical implants, which predetermine acceptance or rejection of implants by the host via pro- and anti-inflammatory polarisation states. The role of chemical signals in macrophage polarisation is well-established, but how physical cues regulate macrophage function that may play a fundamental role in implant-bone interface, remains poorly understood. Here we find that bone marrow-derived macrophages (BMDM) cultured on polyacrylamide gels of varying stiffness exhibit different polarisation states. BMDM are 'primed' to a pro-inflammatory M1 phenotype on stiff substrates, while to an anti-inflammatory M2 phenotype on soft and medium stiffness substrates. It is further observed that matrix stiffening increases Piezo1 expression, as well as leads to subsequent activation of the mechanotransduction signalling effector YAP, thus favouring M1 polarisation whilst suppressing M2 polarisation. Moreover, upon treatment with YAP inhibitor, we successfully induce macrophage re-polarisation to the M2 state within the implant site microenvironment, which in turn promotes implant osseointegration. Collectively, our present study thus characterises the critical role of the Piezo1-YAP signalling axis in macrophage mechanosensing and stiffness-mediated macrophage polarisation and provides cues for the design of immuno-modulatory biomaterials that can regulate the macrophage phenotype.

Effect of arch foot settlement on soil arching in pile-supported embankments under localized surface loading: Numerical damping spring-based trapdoor tests

In most existing trapdoor tests, the supporting structures beneath the arch feet are usually stationary, however, for embankments with flexible or floating piles in deep soft soil areas, piles supporting the arch foot usually settle under vehicle loads, significantly affecting the settlement deformation and load transfer of the embankment. Therefore, A numerical damping spring-based trapdoor model that can account for arch foot settlement is proposed to investigate the effect of arch foot settlement on the soil arching, while comprehensively considering the influence of the interaction among the pile, embankment fill, and soft soil on the evolution of soil arching in a pile-supported embankment. The results show that arch foot settlement on the soil arching differs significantly at different stages: it weakens the soil arching in the initial state and enhances the soil arching in the recovery state but little affects the soil arching in the ultimate state. Moreover, the arch foot settlement significantly reduces the height and stability of the soil arch in relatively high soft soil stiffness conditions, leading to a soil arch that is susceptible to degradation under localized loads. In addition, the arch foot settlement increases the normalized displacement needed for full mobilization of soil arching, resulting in varied levels of mobilization under the same differential settlement.

Bio-inspired soft robot with varied localized stiffness

Soft robots are a type of intelligent robot with high adaptability, and the majority of them are made from soft materials, so they are flexible and adaptable. The variable stiffness function of soft robots is crucial, as it can enhance the robot's adaptability, safety, and dependability. By adjusting the stiffness, the soft robot is able to maintain a stable motion state in a complex environment, reduce environmental interference, and perform human-like actions with improved target control. The elephant trunk served as inspiration for the way proposed in this study for modifying the soft robot's arm's stiffness. By changing the insertion scheme of the interference plate in a flexible manner, the robot arm can have variable bending capability, allowing it to complete a variety of work instructions given by humans and to satisfy a variety of work requirements.

Design and Experiment Investigation on Soft Grippers with Modular Variable Stiffness Structure.

Soft grippers have good adaptability and flexibility for grasping irregular or fragile objects, and to further enhance their stiffness, soft grippers with variable stiffness have been developed. However, existing soft grippers with variable stiffness have the disadvantages of complex structure and poor interchangeability. Here, a soft gripper with modular variable stiffness is proposed that has flexible Velcro embedded in the bottom layer of the soft actuator and one side of the variable stiffness cavity respectively, and both the general and variable stiffness grasping modes are achieved by separation or combination. First of all, according to the neo-Hookean model and the assumption of constant curvature, a free bending model of the soft actuator is established and optimal structural parameters of the soft actuator are obtained by the Genetic Algorithm. Then, influence of the driving pressure on the soft actuator stiffness is investigated, and a mathematical model of the variable stiffness is established. Finally, correctness of the statics model and the stiffness model were verified by experiments. Experimental results indicate that the proposed soft gripper with modular variable stiffness structure has excellent adaptability and stability to different objects, outstanding load bearing capacity, and stiffness adjustment capability.

Clinical Significance of Stiffness during Endoscopic Surgery for Intracerebral Hemorrhage: A Retrospective Study.

Studies regarding hematoma stiffness and removal difficulty are scarce. This study explored the association between hematoma stiffness and surgical results of endoscopic hematoma removal for intracerebral hemorrhage. It also aimed to clarify factors associated with hematoma stiffness. We classified intracerebral hematoma as either soft or firm stiffness by retrospectively evaluating operative videos by two neurosurgeons. The interobserver reliability of the classification was assessed by calculating the κ values. We investigated the relationship between hematoma stiffness and surgical results. Favorable hematoma removal (FHR) was defined as a residual hematoma volume of ≤15 mL or removal rate of ≥70%. Furthermore, we compared the background characteristics, imaging findings, and laboratory data between the two groups. Forty patients were included in this study. The mean baseline hematoma volume was 69.9 mL (range, 41.3-97.6 mL). FHR was accomplished in 35 cases (87.5%). Thirty-four patients (85%) were in the soft hematoma group (group S). Six patients (15%) were in the firm hematoma group (group F). Classification of hematoma stiffness demonstrated an excellent degree of interobserver agreement (κ score = 0.91). Patients in group S had a high FHR rate (p = 0.018) and short endoscopic procedure times (p = 0.00034). The island sign was present in group S (p = 0.030). Patients in group F had significantly high fibrinogen levels (p = 0.049) and low serum total calcium (p = 0.032), hemoglobin (p = 0.041), and hematocrit (p = 0.011) levels. Hematoma stiffness during endoscopic surgery for intracerebral hemorrhage correlates with surgical results, including the endoscopic procedure time and accomplishing rate of FHR.

A novel method to solve the existed paradox of low-frequency vibration isolation and displacement attenuation in a nonlinear floating-slab on the wheel-rail loads

As we have known that it is impossible to attenuate the vibration displacement of the floating-slab depending on a strong stiffness and to improve the low-frequency vibration isolation performance of the floating-slab track (FST) depending on a soft stiffness simultaneously in engineering. In this paper, we propose a novel method to solve the paradox by introducing a “Hardening-First-Then-Softening” (HFTS) design based upon the energy distribution of wheel-rail loads to formulate a model of nonlinear floating-slab isolator. The average procedure is employed to analyze the vibration isolation ability of the isolator with parameters taken from a metro line load excitation. A simulation model of train-FST-tunnel with HFTS isolator is constructed to study the dynamic behaviors of the system. The numerical simulations show the significant suppression of displacement response of floating-slab and Z weighted acceleration vibration level of the tunnel. The results presented herein this paper provide a scheme to solve the strict requirements of displacement suppression and the vibration isolation which is of beneficial to steady and silent urban rail transit.