Maximum Compression Research Articles

A design strategy with the combination of neuro-regression and stochastic optimizations on the hyperelastic gasket

For numerous years, PVC and aluminum doors and windows have been integral components of buildings. The primary technical requisites for doors and windows encompass superior acoustic performance, thermal insulation, and effective sealing. Particularly, the sealing properties, crucially important, are ensured by the gaskets fitted onto the profiles. This paper aims to present a gasket design with a new methodology that includes a systematic modeling-optimization process based on multiple non-linear neuro-regression. Comprehensive research has been done by multiple non-linear neuro-regression analyses of gaskets due to deficient studies in the literature on hyperelastic materials. 17 candidate functional forms based on four basic mathematical structures (polynomial, trigonometric, logarithmic, and linear functions, and their hybrid or rational forms) have been proposed to model the FEM data of the gasket. Hybrid versions of three stochastic search algorithms, Differential Evolution, Random Search, and Simulated Annealing, are considered to solve highly non-linear, non-convex, multi-variables mixed continuous-discrete problems. The experimental results were compared with the numerical result using the finite-element analysis (FEA). Nonlinear static analyses were performed with Abaqus. Stress and logarithmic strain distributions are obtained. A good correlation was found between the experimental and the numerical results The optimum locations and numbers of the nodes have been found to obtain the minimum overflow distance and the maximum compression surface area for gaskets having the same topological structure.

Woven EndoBridge device apposition and compression using Sim&Size virtual simulation correlate with aneurysm occlusion status: a retrospective cohort study

BackgroundVirtual simulation is increasingly used for aneurysm treatment. This study aimed to explore whether mechanical behavior biomarkers of the Woven EndoBridge (WEB) device as computed by Sim&Size simulation software were...

Magnetic Resonance Imaging Parameters in the Subacute Phase after Traumatic Cervical Spinal Cord Injury: A Prospective, Observational Longitudinal Study. Part 1: Conventional Imaging Characteristics.

Magnetic resonance imaging (MRI) remains the gold standard for evaluating spinal cord tissue damage after spinal cord injury (SCI). Several MRI findings may have some prognostic potential, but their evolution over time, especially from the subacute to the chronic phase has not been studied extensively. We performed a prospective observational longitudinal study exploring the evolution of MRI parameters from the subacute to chronic phase after human traumatic cervical SCI. The study, conducted between 2016 and 2021, involved standardized neurological examinations and MRI scans 1 month, 3 months, and 1 year after SCI. The study cohort comprises 52 patients with cervical SCI. Patients were classified into AIS grades (American Spinal Injury Association Impairment Scale), and neurological recovery was assessed using the Integrated Neurological Change Score. The MRI protocol included various routine sequences, allowing the evaluation of established parameters such as intramedullary hemorrhage, lesion dimensions, maximum spinal cord compression, and various grading scales. The persistence of intramedullary hemorrhage one month after injury was associated with worse lower extremity motor scores and pinprick values after 3 months, and also in the chronic phase. In addition, dorsal column T2-weighted hyperintensities detected 3 months post-injury and in the chronic phase were related to lower pinprick sensory scores. The basic score and Sagittal Grade at 1 month were predictive for motor function 3 months after SCI and for neurological recovery between 1 and 3 months after injury. The study contributes valuable insights into the utility of routine MRI sequences for evaluating traumatic cervical SCI during the subacute to chronic phase. The identified MRI parameters and scores offer prognostic information and could support clinical decision-making.

Hydroxyapatite/Silk Fibroin Composite Scaffold with a Porous Structure and Mechanical Strength Similar to Cancellous Bone by Electric Field-Induced Gel Technology.

Repair and regeneration of bone tissue defects is a multidimensional process that has been highly challenging to date. The artificial bone scaffold materials, which play a core role, still face the conflict that a biofriendly porous structure will reduce the mechanical performance and accelerate degradation. Herein, a multistage porous structured hydroxyapatite (HA)/silk fibroin (SF) composite scaffold (e-HA/SF) was successfully constructed by cleverly utilizing electric field-induced gel technology. The results indicated that the prepared e-HA/SF scaffolds possess biomimetic hierarchical porous structures with a suitable porosity similar to that of cancellous bone. The HA nanocrystals were uniformly encapsulated in the three-dimensional space of the composite scaffold, thus endowing the e-HA/SF composite scaffolds with an enhanced mechanical performance. Notably, the maximum compression stress and Young's modulus of e-HA/SF-2 scaffolds can reach 24.66 ± 0.88 and 28.91 ± 3.19 MPa, respectively, which are equivalent to those of cancellous bone. Such mechanical performance enhancement was previously unattainable through conventional freeze-drying strategies. Moreover, the introduction of bioactive nano-HA can trigger the optimal cell response in both static and dynamic cell culture experiments in vitro. The e-HA/SF composite scaffold developed in this study can better balance the conflict between the porous structure and mechanical and degradation properties of porous scaffolds.

Calibration of discrete meta-parameters of bamboo flour based on magnitude analysis and BP neural network.

In the research and development of technology and equipment for bamboo products deep processing, such as filling, drying, and medicinal use of bamboo flour (BF), the poor compaction and fluidity of BF materials entails the need for accurate discrete element model (DEM) and BF parameters to provide a reference for the simulation of BF processing operationsand the development of related equipment. The average particle size of the 5 types of BFs ranges from 0.136 mm to 0.293 mm, and the small particle size of BF particles causes to the number of BF particles in bamboo processing equipment to reach tens of millions or even billions. When conventional methods are used for simulation, ordinary computers cannot provide the required computing power. To address the aforementioned challenges, this paper proposes a calibration method for the discrete element contact parameters of BFs based on dimensional analysis and a back propagation (BP) neural network. Using particle scaling theory and dimensional analysis methods, the average particle size of the BF was increased to 1 mm, and the main discrete element contact parameters of the five types of BF to be tested were used as input layers. The injection method and sidewall collapse method were used to obtain the angle of repose (AR) as the output layer. Fifty groups were randomly selected using MATLAB for EDEM simulation, and the simulation results were trained using the BP neural network algorithm; an ideal neural network model was obtained, the discrete element parameters of different BFs were predicted, and physical experiments were performed to verify two types of AR and mold hole compression under calibrated parameters. The relative error between the simulated AR obtained through calibration parameters and the physical experimental values is less than 2.3%. Through BF parameter validity verification, the simulated maximum compression displacement and compression ratio after stabilization were 34.81 mm and 0.477, which were close to the actual experimental results of 34.77 mm and 0.461, respectively, verifying the accuracy of the neural network prediction model. The research results provide a reference for the simulation of BF processing operations and the development of related equipment.

3D printed polymeric stent design: Mechanical testing and computational modeling

Polymer-based bioresorbable scaffolds (BRS) aim to reduce the long-term issues associated with metal stents. Yet, first-generation BRS designs experienced a significantly higher rate of clinical failures compared to permanent implants. This prompted the development of alternative scaffolds, such as the poly(L-lactide-co-ε-caprolactone) (PLCL) solvent-casted stent, whose mechanical performance has yet to be addressed. This study examines the mechanical behavior of this novel scaffold across a wide range of parallel and radial compression diameters. The analysis highlights the scaffold’s varying responses under different loading conditions and provides insights into interpreting simulation model parameters to accurately reflect experimental results.Stents demonstrated a parallel crush resistance of 0.11 N/mm at maximum compression, whereas the radial forces were significantly higher, reaching up to 1.80 N/mm. Additionally, the parallel test keeps the stent in the elastic regime, with almost no regions exceeding 50 MPa of stress, while the radial test causes significant structural deformation, with localized plastic strain reaching up to 30 %. Results showed that underestimating yield strain in computational models leads to discrepancies with experimental results, being 5 % the most accurate value for matching computational and experimental results for PLCL solvent-casted stents.This comprehensive approach is vital for optimizing BRS design and predicting clinical performance.

Sulfonated corn stalk enhanced hydrogel adsorption for heavy metal from metal mine gallery effluent

There are various of abandoned metal mines in China, and a considerable amount of heavy metal contaminated water is generated through water–rock interactions and accumulated within metal mine gallery. Therefore, the effective removal of heavy metals from metal mine gallery effluent holds significant importance. In this study, sulfonated corn stalk (SCS) and acrylic acid was used to prepare the double network hydrogel SCS-gel. The maximum allowable compression force for the SCS-gel was about 3 times than that of raw hydrogel. The SCS-gel exhibited a stable adsorption capacity within the pH range from 2.0 to 6.0. The maximal adsorption capacities of Pb2+ and Cu2+ on the SCS-gel were 111.6 and 370.2 mg/g, respectively. The functional groups of –OH, C-O, C = O, COOH, and −SO3- were participated in the adsorption process through coordination and electrostatic interactions. The SCS-gel exhibited promising reusability as the adsorption efficiency for Pb2+ and Cu2+ remained at approximately 100 % within 10 cycles of adsorption–desorption. The SCS-gel had an excellent removal efficiency for Pb2+ (99.8 %), Cu2+ (99.1 %), Mn2+ (97.4 %), Zn2+ (98.8 %), and Al3+ (95.7 %) from actual metal mine gallery effluent by dosage of 5 g/L with the initial concentrations of Pb2+, Cu2+, Mn2+, Zn2+, and Al3+ were 4.352, 29.20, 13.02, 7.016, and 30.47 mg/L, respectively. In the fixed-bed experiments, the Thomas model has a good description for the breakthrough curves of these heavy metals. These results confirmed the possibility of adopting SCS ethers for hydrogel fabrication and verified its great potential for the practical application for the removal of heavy metals from metal mine gallery effluent.

Mechanism of low-intensity pulse ultrasound combined with Rhodiola to promote bone formation in spinal fusion.

This study aimed to explore the influence and mechanism of low-intensity pulsed ultrasound (LIPUS) combined with Rhodiola bone penetration on the formation of spinal fusion bone. Sixty clean-grade New Zealand white rabbits were selected for randomization and divided into combined group and Rhodiola group, with 30 rabbits in each group to construct a rabbit lumbar intervertebral fusion model, using Rhodiola intervention and Rhodiola combined with LIPUS intervention protocol, respectively. The axial strength, axial stiffness, maximum compressive load, vascular endothelial growth factor (VEGF), cycloxygenase-2 (COX-2), prostaglandin E2 (PGE2) and transforming growth factor-β (TGF-β) were compared after HE staining, immunohistochemistry and biomechanical detection. Spine fusion rate was 100.00%; the combined bone graft tissue had implanted bone cell degeneration, cell necrosis and cell hyperplasia, chondrocytes differentiated into trabecular bone and some hematopoietic cells, severe cell necrosis and fiber cell proliferation and late bone formation in the Rhodiola group, VEGF, COX-2, PGE2, TGF-β, axial strength, axial stiffness, and maximum compression load in the combined group significantly increased (P<0.05). Spinal fusion using LIPUS combined with Rhodiola can enhance biomechanical properties and promote the role of PGE2, COX-2, VEGF, TGF-β expression and bone formation, and this protocol is worthy of clinical application.

ANALYSIS OF THE EFFECTIVENESS OF INDIRECT SPINAL CANAL DECOMPRESSION IN THE TREATMENT OF BURST FRACTURES AT THE THORACOLUMBAR JUNCTION

Indirect decompression of the spinal canal through ligamentotaxis is one of the methods for remodeling the spinal canal in traumatic stenosis. Objective: To evaluate the effectiveness of indirect decompression of the spinal canal for different morphological types of burst fractures of vertebral bodies at the thoracolumbar junction. Methods. A preoperative and postoperative analysis of computed tomography scans was performed on 59 patients who were treated at the«Romodanov Neurosurgery Institute, National Academy of Medical Sciences of Ukraine» for burst fractures at the thoracolumbar junction. The criterion for the effectiveness of indirect decompression was the area of the spinal canal, measured at the level of injury in the zone of maximum compression. The grading of burst fractures was performed using the classification by F. Magerl et al. (1994). Results. In the preoperative period, the median degree of stenosis in the group of patients was 43.47 % (95 % confidence interval (CI): 37.53–46.22 %). For damage type A3.1, it was 36.9 % (95 % CI: 28.1‒40.5 %), for type A3.2 — 46.1 % (95 % CI: 32.1‒54.5 %), and for type A3.3 — 47.6 % (95 % CI: 37.5‒56.5 %). After surgical treatment, the degree of stenosis decreased by 20.14 % (95 % CI: 15.93‒21.56 %). For type A3.1, the effectiveness was 20.1 % (95 % CI: 9.5‒22.7 %), for type A3.2 — 15.2 % (95 % CI: 7.51‒17.3 %), and for type A3.3 — 21.7 % (95 % CI: 20.8‒26.4 %). The difference between types A3.2 and A3.3 was statistically significant (p = 0.0018). It was found that indirect decompression is most effective with higher degrees of stenosis. For Grade I by D. Wolter (1988), the canalexpansion achieved was 7.07 % (95 % CI: 5.69‒8.65 %), for Grade II — 21.6 % (95 % CI: 20.4‒22.7 %), and for Grade III — 30.3 % (95 % CI: 27.0‒33.6 %). Conclusions. Closed remodeling of the spinal canal with transpedicular fixation and the effect of ligamentotaxis is an effective method for correcting traumatic spinal canal stenosis at the thoracolumbar junction. The effectiveness of the technique is determined by many factors, including the type of burst fracture, the initial degree of stenosis, and the level of injury.

Tract-specific magnetization transfer ratio provides insights into the severity of degenerative cervical myelopathy.

Cross-sectional study. This study's goal is to report whether Magnetization Transfer Ratio (MTR) can evaluate the severity of white matter (WM) injury in degenerative cervical myelopathy (DCM). Laureate Institute of Brain Research, USA; Department of Neurosurgery, University of Oklahoma Health Sciences Center, USA. 27 DCM patients were aged-matched with 20 healthy controls (HC) and categorized into treatment groups based on modified Japanese Orthopedic Association (mJOA) severity (11 mild and 16 moderate/severe). Regional and tract MTRs were extracted from the two vertebral levels containing maximum compression within magnetization transfer images. MTR differences between groups were assessed using a one-way ANOVA or Kruskal-Wallis test. The association between MTR and mJOA measures was evaluated using Spearman's correlation. Significant decreases in MTR were found between HC and moderate/severe groups in the overall (p = 0.0065) and ventral (p = 0.0009) WM regions; and ventral corticospinal (p = 0.0101), ventral reticulospinal (p = 0.0084), spinal lemniscus (p = 0.0079), and fasciculus cuneatus (p = 0.0219) tracts. The spinal lemniscus MTR also significantly decreased between HC and mild groups (p = 0.038). Ventral reticulospinal tract MTR correlated with upper (r = 0.439; p = 0.022) and lower (r = 0.386; p = 0.047) limb motor mJOA scores. Significant tract-based MTR changes and correlations align with known DCM symptoms, are demonstrated to be lost at the regional level, and display the inhomogeneous compressive damage occurring within DCM spinal cords.

Thermal Transport and Thermal Polarization of Water in the Supercooled Regime.

The behavior of water in the deep supercooled regime has attracted significant interest, motivated by the hypothesis of the second critical point of water. Previous studies indicated the existence of a water anomaly, characterized by a minimum in the thermal conductivity of water. Here, we employ nonequilibrium molecular dynamics computer simulation and the TIP4P/2005 water force field to investigate the thermal conductivity of supercooled water targeting four different isobars, 1, 200, 700, and 1200 bar. We demonstrate using NEMD simulations the existence of minima in thermal conductivity associated with the maximum isothermal compressibility and the minimum speed of sound in water, hence establishing a firm connection with the second critical point of liquid water. Moreover, we demonstrate that thermal gradients polarize supercooled water with a thermal polarization coefficient of several mV/K. We explain the thermal polarization effect using a theoretical formulation introduced recently that connects the thermal polarization effect to the isobaric thermal expansion coefficient.

On the elastoplastic behavior in collisional compression of spherical dust aggregates

Aggregates consisting of submicron-sized cohesive dust grains are ubiquitous, and understanding the collisional behavior of dust aggregates is essential. It is known that low-speed collisions of dust aggregates result in either sticking or bouncing, and local and permanent compaction occurs near the contact area upon collision. In this study, we perform numerical simulations of collisions between two aggregates and investigate their compressive behavior. We find that the maximum compression length is proportional to the radius of aggregates and increases with the collision velocity. We also reveal that a theoretical model of contact between two elastoplastic spheres successfully reproduces the size- and velocity-dependence of the maximum compression length observed in our numerical simulations. Our findings on the plastic deformation of aggregates during collisional compression provide a clue to understanding the collisional growth process of aggregates.Graphic abstract

Enhanced mechanical properties of LPSOp/Mg composites using super high pressure treatment

The super high pressure (SHP) technique was employed to fabricate the magnesium matrix composites (MMCs) reinforced with long-period stacking order structure powder (LPSOp) by cubic-anvil large-volume press with six rams. The LPSOp was optimized through high energy ball milling (HEBM) with a chemical composition of Mg85Zn6Y9 (at%). The microstructure and mechanical properties of LPSOp/Mg composite was characterized by X-ray diffraction (XRD), scanning electron microscopy/transmission electron microscopy (SEM/EDS), transmission electron microscopy (TEM), microhardness and compressive tests. The microhardness of LPSOp exhibits a notable increase after HEBM, and the thermal stability of LPSOp is affirmed through elevated annealing. The SHPed LPSOp/Mg consists of Mg and LPSO phase. Upon annealing at 400 °C for 1 h, the LPSO phase precipitates from solid solution of Mg and W phase is also identified. The strength of composites by SHP treatment and subsequently annealing is significantly improved compared with the pure Mg without LPSOp, which demonstrates the maximum compression yield strength (CYS) of 250 MPa and ultimate compression strength (UCS) of 375 MPa with satisfactory ductility. The enhanced mechanical properties are attributed to the synergistic reinforcement effects of the dispersed and 3D skeletal structure of LPSOp with excellent interfacial bonding, the coexistence of nano-scale LPSO and W phase and partial solid solution strengthening.

Effect of Defatted Rice Bran Content on Physicochemical and Sensory Properties of Edible Cutlery Made from Rice Flour Green Composites using Compression Molding

The optical properties, moisture content, water activity, water absorption, mechanical properties, morphological observations, and sensory properties of edible spoons made from rice flour and rice flour green composites were investigated. The rice flour green composites were prepared with different weight ratios of rice flour and defatted rice bran as 100:0, 75:25, 50:50, and 25:75 by compression molding at 150°C at a fixed pressure of 9 bar for 7 min. Increasing the weight proportion of defatted rice bran in rice flour green composites resulted in higher lightness values, yellowness values, and water absorption, but redness values and moisture content decreased. Weight proportions of defatted rice bran in rice flour green composites up to 50 improved mechanical properties (both Izod impact and flexural strength). The cross-sectional surface after flexural testing of rice flour spoons was smooth, whereas rice flour green composite spoons were rough. Sensory properties of rice flour green composite spoons showed reduced appearance scores, color scores, texture scores, and overall preference scores but odor scores increased compared with rice flour spoons. Maximum compression force of rice flour green composite spoons increased with increasing weight proportion of defatted rice bran. An increase in maximum compression force measured by the mechanical testing equipment was related to a decrease in texture scores. Spoons made from rice flour and rice flour green composites showed promise as single-use edible cutlery and packaging.

Formation of high areal density core using an efficient and robust implosion method for fast ignition

Abstract A new fuel compression method for a fast ignition scheme is discussed. To form a high areal density fuel plasma for the ignition condition, homogenous isentropic compression (HIC) with solid spherical target is effective. We improve a multi-step pulse shape method that uses progressive shockwaves and reflected shockwaves for the compression, where a precisely controlled step-pulse laser drives the shockwaves to compress the fuel and suppress entropy increase. Another advantage of this approach is the relatively smooth high dense fuel is distributed at maximum compression time, compared to our previous design based on Kidder’s HIC method. In addition, we insert a power dip as a preconditioning before the last pulse step to reduce the electron and ion temperature near critical density. As a result, an optimum implosion is designed using 245 kJ of implosion laser energy to meet the ignition condition.

A biomechanical study comparing the compression force and osseous area of contact of two screws fixation techniques used in ankle joint arthrodesis model

IntroductionArthrodesis of a (diseased) ankle joint is usually performed to achieve pain relief and stability. One basic principle of arthrodesis techniques includes rigid fixation of the surfaces until union. It seems plausible that stable anchoring and homogeneous pressure distribution should be advantageous, however, it has not been investigated yet. The aim is to achieve uniform compression, as this is expected to produce favorable results for the bony fusion of the intended arthrodesis. Numerous implants with different biomechanical concepts can be used for ankle fusion. In this study, headless compression screws (HCS, DePuy Synthes, Zuchwil, Switzerland) were compared biomechanically to an alternative fixation System, the IOFix device (Extremity Medical, Parsippany, NJ, USA) in regard to the distribution of the compression force (area of contact) and peak compression in a sawbone arthrodesis-model (Sawbones® Pacific Research Laboratories, Vashon, WA, USA).This study aims to quantify the area of contact between the bone interface that can be obtained using headless compression screws compared to the IOFix. In current literature, it is assumed, that a large contact surface with sufficient pressure between the bones brings good clinical results. However, there are no clinical or biomechanical studies, that describe the optimal compression pressure for an arthrodesis.Material and methodsTwo standardized sawbone blocks were placed above each other in a custom-made jig. IOFix and headless compression screws were inserted pairwise parallel to each other using a template for a uniform drilling pattern. All screws were inserted with a predefined torque of 0.5 Nm. Pressure transducers positioned between the two sawbone blocks were compressed for the measurement of peak compression force, compression distribution, and area of contact.ResultsWith the IOFix, the compression force was distributed over significantly larger areas compared to the contact area of the HCS screws, resulting in a more homogenous contact area over the entire arthrodesis surface. Maximum compression force showed no significant difference.ConclusionThe IOFix system distributes the compression pressure over a much larger area, resulting in more evenly spread compression at the surface. Clinical studies must show whether this leads to a lower pseudarthrosis rate.

Assessment of geomechanical properties of Sakhalin shelf reservoirs based on modeling results

Background. Due to the complex tectonic structure of the Sea of Okhotsk shelf and intense geodynamic activity in this area, specialized technologies are required to study reservoir properties. In this work, we implement the technology of secondary permeability estimation using the Kirinskoye and Ayashskoye license blocks as an example. The research objects included structural and lithologic traps of different complexes. It was found that the Prisakhalin shelf, including the Kirinsky and Ayashsky license areas, is subject to the modern shear stress field with the sublatitude-oriented axis of maximum compression. This initiates the formation of a local stress field, launches changes in the degree of fracture openness, and determines the secondary porosity and permeability of rocks. 3D modeling allowed us to calculate predicted permeability for each stratigraphic horizon. A significant difference of secondary permeability in the upper and lower stratigraphic horizons is noted.Aim. To evaluate secondary filtration and capacitance properties of reservoirs by geomechanical modeling.Materials and methods. Geomechanical modeling to assess the filtration and capacitance properties of Sakhalin shelf reservoirs was carried out using the ROXAR software package.Results. This work allowed not only the filtration efficiency to be predicted, but also the processes occurring in the geological section of the shelf of the Sea of Okhotsk to be elucidated.

Prognostic Value of Magnetic Resonance Imaging Variables Combined with Neutrophil-to-Lymphocyte Ratio in Patients with Cervical Traumatic Spinal Cord Injury

We aimed to explore the prognostic significance of preoperative magnetic resonance imaging (MRI) variables and novel inflammatory indicators in predicting neurological recovery post-cervical traumatic spinal cord injury (TSCI) in the study. We enrolled a total of 244 patients diagnosed with acute cervical TSCI from two hospitals and evaluated the prognostic value of MRI variables (intramedullary hemorrhage, intramedullary lesion length (IMLL), maximum spinal cord compression (MSCC), and maximum canal compromise (MCC)) and novel inflammatory indicators (neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR), and systemic immune-inflammatory index (SII)) in patients with acute cervical TSCI. Among the 244 patients, 140 (57.38%) exhibited improved AIS grade conversion at 1-year follow-up. The results revealed intramedullary hemorrhage, IMLL, MCC, neutrophils, and NLR were significantly different compared with follow-up AIS grade. Furthermore, IMLL, MCC, WBCs, neutrophils, NLR, and LMR correlated with the follow-up AIS grade by Spearman’s correlation analysis. Multivariate analysis showed IMLL, intramedullary hemorrhage, NLR and admission AIS grade emerged as independent predictors of AIS grade conversion. The receiver operating characteristic curve (ROC) analysis showed that the novel model (combination of MRI variables, NLR and admission AIS grade) produced a larger area under the curve compared with using only intramedullary hemorrhage, IMLL, NLR or admission AIS grade individually. In conclusion, intramedullary hemorrhage and IMLL and NLR are predictors of AIS grade conversion after cervical TSCI. Therefore, we suggest the combination of MRI variables and NLR for the prognostic prediction of AIS grade conversion in patients with cervical TSCI.

Research and Prediction of Wear Characteristics of Alfalfa Densification Die Based on the Discrete Element Method

In this study, the wear characteristics of the die were tested and analyzed through compaction tests, and the distribution of wear depth along the direction toward the extrusion outlet was obtained. A discrete element method (DEM) model of the die’s wear process was established. The results show that the severe wear area is located near the stop position of the compression rod, forming a plow-shaped wear area along the extrusion direction, accompanied by fatigue peeling. The wear depth gradually decreases towards the extrusion outlet. The DEM model partially reveals the occurrence of the wear phenomenon, but the particle motion speed deviates from the actual situation. The maximum compression force value range during the DEM compression stage is within the actual maximum compression force value range, and the relative error range of the average maximum compression force is less than 2%. By verifying the formula to calibrate the model, the calibrated model is compared with the actual mold wear, and the predicted value is close to the actual test result. The DEM can be used to explore the wear mechanism and predict the die’s wear failure process, laying the foundation for optimizing die wear resistance design.

Strength, plasticity, and spin transition of Fe-N compounds in planetary cores

Elastic and plastic properties of Fe-light element alloys and compounds are needed to determine the compositions and dynamics of planetary cores. Elastic strength and plastic deformation mechanisms and their relationship to electronic properties of ε-Fe7N3 and γ'-Fe4N mixture were investigated by x-ray diffraction and x-ray emission spectroscopy in the diamond anvil cell from 1 bar up to 60 GPa. X-ray diffraction shows that ε-Fe7N3 reaches a pressure of 15–20 GPa before undergoing bulk plasticity at a differential stress of 4.4–10.4 GPa. ε-Fe7N3 is stronger than γ'-Fe4N and hcp-Fe which achieve a flow stress of 1.5–3.6 GPa at 10–15 GPa and 2–3 GPa at ∼20 GPa, respectively. X-ray emission spectroscopy shows that a decrease in electronic spin moment begins before and completes after plastic flow onset for each nitride, suggesting that pressure-driven changes in electronic arrangement do not trigger a plastic response although they may modify the strength and plastic behavior of Fe-N compounds. Plastic deformation in ε-Fe7N3 and hcp-Fe results in a preferred orientation of (0001) normal to maximum compression, while γ'-Fe4N develops a maximum in the (110). These observations may be combined with measurements of elasticity to model seismic properties of cores of small planetary bodies such as Mars, Mercury, and the Moon.