Stable Construct Research Articles

How wide of a distal metaphyseal femoral fracture gap is a high risk of varus collapse and fixation failure? A finite element study.

Severe metaphyseal comminution and sizable bone defect of the distal femur are high risks of fixation failure. To date, no exact magnitude of comminution and bone loss is determined as an indication for augmentation of fixation construct. The present study aimed to investigate the influence of metaphyseal gap width, working length, and screw distribution on the stability of the fixation construct. A finite element model of a fractured femur with 0-80 mm metaphyseal gap width stabilized by an 11-hole distal femur locking compression plate (LCP-DF) was generated. The different working length and screw distribution were created by three different screw configurations: 9-10-11 (long working length, cluster screw), 8-10-11, and 7-9-11 (short working length, spreading screw). Physiological loading conditions were applied to evaluate biomechanical performance including equivalent von Mises (EQV) stress, bone stress, and fracture strain. The EQV stress increased accordingly to a metaphyseal gap width of 0-20 mm. The EQV stress values were at the same levels for 30-mm metaphyseal gap width and higher, particularly in screw configuration 9-10-11. Screw configuration 7-9-11 produced the lowest elastic strain. A 0-mm metaphyseal gap width presented the lowest bone stress. Bone stress values were in a similar magnitude across a 10-80 mm metaphyseal gap. The 30-mm and wider metaphyseal gap width with a long working length presented a risk of varus collapse and fixation failure. Short working length with spreading screw provided low EQV stress, low bone stress, and high fracture stability.

Rescue of Interfragmentary Compression in Screw Stripping Failures: The Efficacy of NiTiNOL.

Orthopedic screws are widely used to achieve bone reduction, compression, and construct stability. However, the relationship between insertion torque, interfragmentary compression, and fixation strength, especially when comparing standard screws with NiTiNOL/sustained dynamic compression (SDC), has not been thoroughly investigated. This study measured insertion torque, interfragmentary compression, and fixation strength for two types of headed orthopedic devices-standard and SDC-using solid foam bone replicates and cadaver validation. The study also assessed the interfragmentary compression produced by these devices in the context of simulated bone resorption. Results showed that compression force increased with insertion torque until thread stripping occurred, resulting in a 91.9% loss of compression in the standard screw group. In contrast, the SDC device maintained significantly higher compression, even beyond the point of stripping. These findings suggest that SDC devices offer increased safety by continuing to apply interfragmentary compression after stripping. The SDC device's ability to generate internal compression allows it to re-engage threads into undamaged bone, potentially compensating for compression loss due to stripping. Clinically, these results indicate that surgeons might benefit from deliberately undershooting peak insertion torque, regardless of the device type, and may prefer NiTiNOL-based SDC devices for their resilience to stripping and bone resorption, ultimately optimizing patient outcomes in foot and ankle surgery.

Synergizing bioprinting and 3D cell culture to enhance tissue formation in printed synthetic constructs.

Bioprinting is currently the most promising method to biofabricate complex tissues in vitro with the potential to transform the future of organ transplantation and drug discovery. Efforts to create such tissues are, however, almost exclusively based on animal-derived materials, like gelatin methacryloyl, which have demonstrated efficacy in bioprinting of complex tissues. While these materials are already used in clinical applications, uncertainty about their safety still remains due to their animal origin. Alternatively, synthetic bioinks are developed that match the printability of natural bioinks but lack their biological complexity, and thereby often fail to support cell growth and facilitate tissue formation. Additionally, most synthetic materials do not meet the mechanical demands to bioprint stable constructs while providing a suitable environment for cells to grow, limiting the number of available bioinks. To bridge this gap and synergize bioprinting and 3D cell culture, we developed a PEG-based bioink system to promote the growth and spreading of cell spheroids that consist of human primary endothelial cells and fibroblasts. The 3D bioprinted centimeter-scale constructs have a high shape fidelity and accelerated softening to provide sufficient space for cells to grow. Adjusting the rate of degradability, induced by the integration of ester-functionalized crosslinkers in addition to protease cleavable crosslinkers into the hydrogel network, improves the growth of spheroids in larger printed hydrogel constructs containing an interconnected channel structure. The perfusable constructs enable extensive spheroid sprouting and the formation of a cellular network upon fusion of sprouts as initial steps towards tissue formation with the potential for clinical translation.

Increased stiffness with medial column screw supplementation of lateral locking plate for distal femur fractures: a biomechanical study.

We propose and assess the biomechanical stability of medial column screw supplementation in a synthetic distal femur fracture model. Twenty-four low density synthetic femora modeling osteoporotic, intraarticular distal femur fractures with medial metaphyseal comminution were split into two fixation groups: (1) lateral locking distal femur plate (PA- plate alone) and (2) lateral locking distal femur plate with a 6.5mm fully threaded medial cannulated screw (PWS- plate with screw). Cyclic biomechanical testing included 5 steps of 10,000 cycles with each step increasing axial loads starting at 0.5xBW (BW = 80kg) up to 2.5xBW. Discrete stiffness was calculated for each step and cumulative stiffness was calculated across the entire protocol. Outcomes of interest included cumulative stiffness, discrete stiffness, and instrumentation failure. Seven of the PA models had failure during testing. No failures were seen in the PWS group. PWS had 19.8% higher cumulative stiffness compared to PA (676.3 N/mm vs 809.8 N/mm; P = 0.014). Discrete stiffness showed < 1% differences at lower loads, but increasing loads found the PWS group with 12% greater discrete stiffness than the PA group (879.1 N/mm vs 983.8 N/mm; P = 0.028). This is the first study to evaluate the contribution of a medial column screw in a distal femur fracture model. PWS had superior stiffness and few failures compared to PA. Applied clinically, a medial column screw can increase construct stability in the setting of complex distal femur fractures with minimal increase in operative time, patient morbidity and cost.

Suture button systems for coronoid fracture fixation: a biomechanical time-zero pilot study

PurposeThis study aims to describe a fixation technique for coronoid fractures using suture buttons, and to biomechanically evaluate this technique in comparison to screw fixation as a time-zero pilot study.MethodsAn O’Driscoll type 2 anteromedial coronoid facet (AMCF) fracture was simulated in 20 fresh-frozen human elbows. The specimens were randomized into two groups and fracture fixation was performed with either a suture button system or a 3.5 mm cannulated screw. Ultimate load-to-failure (N) was then tested for each specimen.ResultsThe mean load-to-failure was 322.6 ± 75.9 N for suture button fixation and 314.2 ± 85.9 N for screw fixation. The differences were not statistically significant (p = 0.432). Additional fracturing of the coronoid fragment was observed in two specimens with screw fixation.ConclusionPromising biomechanical evaluations show that this fixation technique using suture buttons in the treatment of coronoid fractures provides equal construct stability as screw fixation. Further studies are required to fully validate this procedure.

Investigating the stability of chimeric murine polyomavirus VP1 Capsomeres via molecular dynamics simulations and experimental analysis

The development of modular virus-like particle (VLP) vaccine platforms with genetically inserted antigens in viral structural proteins shows great promise for advancing vaccine technology. However, the instability of many constructs leads to trial-and-error approaches, and the challenge of predicting stability based solely on amino acid sequences remains unresolved, yet highly appealing. This study evaluates the stability of wild-type murine polyomavirus (MPV) VP1 capsomeres and three engineered chimeric variants using molecular dynamics (MD) simulations and laboratory experiments. MD simulations, based on AlphaFold2 predictions and up-to-date all-atom force fields, accurately predicted the thermal stability and hydrophobicity of VP1-based capsomeres. Thermodynamic analysis revealed that binding energies from simulations reliably indicate thermal stability. Experiments and simulation results showed that inserts influence the stability of capsomeres differently, with larger insertions generally having a greater impact on the structures of capsomeres. This leads to increased intra-subunit distances and a higher proportion of flexible regions in the capsomere chassis. Capsomeres with less compact structures were found to have lower thermal stability. Specifically, the thermal transitional temperature (Tm) of the wild-type capsomeres was 46.9 °C, while the Tm values of the three chimeric derivatives were 42.0 °C, 38.8 °C, and 37.7 °C, reflecting a correlation between decreased thermal stability and reduced structural compactness. This research presents a robust approach for predicting the stability of novel VLP constructs based on amino acid sequences, potentially enhancing vaccine design by reducing failures, and suggests a shift towards minimal epitope insertions for improved stability.

Turning Lemons into Lemonade: Mediating Collaborative Innovation through Digital Transformation for Sustainable Entrepreneurship

This study employs structural equation modelling and a 5-point Likert scale to examine the relationship among Digital Transformation, Collaborative Innovation, and Sustainable Entrepreneurship. Utilising Variance Inflation Factors (VIF) for collinearity assessment, the inner model demonstrates stable construct relationships despite moderate VIF values. When collinearity is evaluated using Variance Inflation Factors (VIF), the inner model shows robust construct correlations even with moderate VIF values. The results of path coefficient analysis show that collaborative innovation and digital transformation have a major, beneficial impact on sustainable entrepreneurship. The psychometric assessments ensure the reliability and validity of the constructs in the measurement model. The model selection of the study based upon Bayesian Information Criterion (BIC), sustains the efficacy of models, incorporating Collaborative Innovation and Sustainable Development by accentuating their critical charities to accomplish a frugal and effective model fit, vibrant for understanding multifarious phenomena. Specifically, f-square values highlight the practical significance of effect size measurements. Overall, this study offers a clear knowledge of the connections between these important concepts, which will be helpful for practitioners and policymakers as they promote sustainable entrepreneurship through collaborative innovation and digital transformation.

Bone Tissue Engineering With Chitosan, Carbon Nanotubes, and Hydroxyapatite Biomaterials Enriched With Mesenchymal Stem Cells: A Radiographic and Histological Evaluation in a Sheep Model Undergoing Ostectomy (Bone Tissue Engineering in a Sheep Model).

Comminuted fractures associated with tissue loss can adversely affect bone regeneration. Biomaterials enriched with mesenchymal stem cells (MSCs) employed for supporting osteosynthesis and potentiating osteoconduction are necessary to fill these bone defects. Natural compound biomaterials, similar to bone tissue, have been extensively tested in animal models for clinical use. Bone tissue engineering studies have used critical-size defects in ovine tibia monitored by imaging and histological examinations to evaluate the regenerative process. This study aimed to monitor the regenerative process in ovine tibial defects with or without chitosan, carbon nanotubes, or hydroxyapatite biomaterials, enriched or not enriched with MSCs. A 3-cm ostectomy was performed in 18 female Suffolk sheep. A 10-hole 4.5 mm narrow locking compression plate was used for osteosynthesis. The animals were randomly divided into three groups (n = 6): control (CON); defects filled with chitosan, carbon nanotubes, and hydroxyapatite biomaterial (BIO); and the same biomaterial enriched with bone marrow MSCs (BIO + CELL). The animals were evaluated monthly using radiographic examinations until 90 postoperative days, when they were euthanized. The limbs were subjected to micro-computed tomography (micro-CT), and bone specimens were subjected to histological evaluations. The radiographic examinations revealed construction stability without plate deviation, fracture, or bone lysis. Micro-CT evaluation demonstrated a difference in bone microarchitecture between the CON and biomaterial treatment groups (BIO and BIO + CELL). In the histological evaluations, the CON group did not demonstrate bone formation, and in the treatment groups (BIO and BIO + CELL), biocompatibility with sheep tissue was noted, and bone formation with trabeculae interspersed with remnants of the biomaterial was observed, with no differences between the groups. In conclusion, biomaterials present osteoconduction with beneficial characteristics for filling bone-lost fractures, and MSCs did not interfere with bone formation.

Homological stability for spaces of subsurfaces with a tangential structure

Abstract Given a manifold with a boundary, one can consider the space of subsurfaces of this manifold meeting the boundary in a prescribed fashion. It is known that these spaces of subsurfaces satisfy homological stability if the manifold has at least dimension five and is simply connected. We introduce a notion of tangential structure for subsurfaces and give a general criterion for when the space of subsurfaces with a tangential structure satisfies homological stability, provided that the manifold is simply connected and has dimension $n\geq 5$. Examples of tangential structures such that the spaces of subsurface with that tangential structure satisfy homological stability are framings or spin structures of their tangent bundle or k-frames of the normal bundle, provided that $k\leq n-2$. Furthermore we introduce spaces of pointedly embedded subsurfaces and construct stabilization maps, as well as prove homological stability for these. This is used to prove homological stability for spaces of symplectic subsurfaces.

Characterization of Thermal and Stress Dual-Induced Nano-SiC-Modified Microcapsules

This work reports a kind of thermal and stress dual-induced nano-SiC-modified microcapsule that is applied to asphalt pavement to improve its self-healing performance. For this purpose, the microcapsules needed to contain a regenerator and be stable in an asphalt mixture. In addition, the microcapsules needed to have good wave-absorbing and temperature-raising properties to realize the dual-mechanism-induced release of microcapsules. In the first step in this study, heat-stressed double microcapsules were prepared. Then, the properties of the microcapsules—including basic properties, stability, mechanical properties, and wave-absorbing and temperature-raising properties—were tested. Finally, the self-healing mechanism of the microcapsules was observed. The results show that the nano-SiC-modified microcapsules have a high core content (87.6%), suitable particle size (average particle size of 53.50 µm), high thermal stability (mass loss of 2.92% at 150~170 °C), high construction stability (survival rate of more than 80%), high storage stability (loss rate of 2.35% at 49 d), and high mechanical properties (Young’s modulus and nano-hardness of 3.15 Gpa and 0.54 Gpa, respectively). Compared with microcapsules without nano-SiC, the thermal conductivity of the 10% nano-SiC-modified microcapsules increased by 21.6%, their specific heat capacity decreased by 10.45%, and their thermal diffusion coefficient increased by 36.96% after microwave heating for 6 min.

Research on the Influence of Shallow Buried Tunnel Crossing on the Stability of Overlying Frame Structure Building

The land section of the Huangdao end of the Jiaozhou Bay Second Submarine Tunnel is extensively underlain by the Quaternary Loose Accumulation Layer. The tunnel passes through a weathered granite fracture zone with well-developed rock joints beneath the buildings. The tunnel excavation process significantly disturbs the buildings above, making them prone to settlement, cracking, and tilting. This research conducts numerical simulations of three tunnel excavation methods, and based on the results, compares the deformation behaviors of the ground surface and buildings under various conditions. The findings show that the double side-wall guide pit method has better adaptability in controlling surface settlement and building deformation than the vertical or curved CD method. Moreover, the removal of temporary supports significantly affects building settlement and tilt; this risk can be effectively reduced by controlling the stress relief ratio during the removal phase of the temporary supports in the tunnel. The significance of the study lies in the fact that by choosing an appropriate tunnel excavation support scheme, the disturbance impact on the overlying buildings can be minimized, and the construction safety and stability of the surrounding buildings can be guaranteed. The results of this study can provide initial guidance for constructing shallow-buried tunnels beneath existing buildings.

Current surgical treatment concepts for traumatic thoracic and lumbar vertebral fractures in adults with good bone quality

The surgical treatment of traumatic vertebral body fractures in patients with good bone quality is controversially discussed. The data situation is unclear and only of limited help due to mainly insufficient evidence. The surgical measures include an axially aligned reduction and an osteosynthesis which is stable under load so that immediate mobilization of the patient is possible. This requires anatomical restoration of the alignment and the biomechanical challenge of fracture healing or fusion in the correct position without relevant loss of reduction must be taken into account. The aim should be the lowest possible loss of function. In the case of existing or impending neurological deficits it is crucial to prevent deterioration of the neurological situation and to achieve the prerequisites for recovery. Posterior stabilization primarily plays the decisive role in the operative treatment. If possible, this should be a minimally invasive procedure and over short distances. For bisegmental treatment monoaxial screws and the use of index screws improve construct stability. In addition, stable cobalt rods should be used as 5mm longitudinal support. Special minimally invasive reduction instruments are helpful in restoring the sagittal and coronal relationships. The indications for an additional ventral column depend on the rigidity of the posterior stabilization, the extent of the injury of the anterior column and the intervertebral disc. Anterior fusion can often be delayed or avoided altogether, depending on the course with corresponding clinical signs.

Sequential Anterior Longitudinal Ligament Release With Expandable Spacers for Lordosis Correction in Anterior-to-Psoas Lumbar Interbody Fusion: A Radiographic and Biomechanical Study.

Anterior column realignment is an attractive minimally invasive treatment for sagittal imbalance. Expandable spacers offer controlled tensioning of the anterior longitudinal ligament (ALL) during release, which could optimize correction and anterior column stability. This study investigated the biomechanical and radiographic effects of single-level anterior-to-psoas lumbar interbody fusion (ATP-LIF) with expandable spacers and sequential ALL release. In vitro range of motion tests were performed on 7 fresh-frozen cadaveric spines (L2-L5) with a ±7.5 Nm load applied in flexion-extension (FE), lateral bending (LB), and axial rotation (AR). After testing intact spines, single-level (L3-L4) ATP-LIFs were performed and supplemented with posterior screws, rods, and integrated lateral screws and tested after (1) no ALL release (ATP-LIF); (2) resection of 1/3 the ALL's width (1/3 ALL release); (3) resection of 2/3 the ALL's width (2/3 ALL release); and (4) complete ALL resection (3/3 ALL release). Following each partial ALL release, rods were removed, and spacers were expanded until the torque limit was reached. Rods were then reapplied, and lateral radiographs were taken to analyze changes in intervertebral angle (IVA), foraminal height, foraminal area, and posterior and anterior disc height (PDH and ADH). In ATP-LIF constructs, range of motion decreased in FE (18% intact), LB (14% intact), and AR (30% intact), while IVA, PDH, ADH, foraminal height, and foraminal area increased. PDH and ADH increased linearly with sequential ALL release and spacer expansion, while LB and AR remained stable. FE increased slightly (+15%-16% intact, <1°) following 2/3 ALL release but remained stable afterward. IVA increased exponentially with sequential ALL release, gaining 8.8° ± 3.2° with complete release. The present study found improved biomechanics and radiographic parameters following ATP-LIF with intact ALL, minimal biomechanical differences between partial and complete ALL release, and greater correction and height restoration with complete release. Future clinical testing is necessary to determine the impact of this finding on patient outcomes. Controlled tensioning of the ALL before and after ligament release allows for potential optimization between restoring sagittal balance and maximizing construct stability in a minimally invasive approach.

Structural Antibiotic-Coated Hindfoot Nail Preparation: A Technique Guide

The current guide describes a technique that has been in place at the University of Louisville for several years and has been utilized to create structural antibiotic hindfoot nails. This has the intention of creating a stable construct that can be utilized in the setting of previous osteomyelitis, or that is at high risk of developing infections in the postoperative state. This technique guide provides a reproducible way to apply an antibiotic delivery system to a tibiotalocalcaneal nail at the time of definitive surgical intervention. It described our method at rural state level one trauma hospital of utilizing antibiotic-impregnated polymethylmethacrylate around a nail for both antibiotic properties as well as structural properties. Antibiotic delivery systems are a well-researched surgical tool, combining this with a hindfoot nail offers definitive surgical management of otherwise complicated surgical cases. Although this technique has been in use at the University of Louisville for many years, additional research should be done to determine long-term outcomes. Level of Evidence: Diagnostic Level VII. See Instructions for Authors for a complete description of levels of evidence.

Geotechnical identification of soil deposits and clay sensitivity evaluation: A case study from East Algeria

This article provides an overview of a comprehensive study conducted in the Tebessa region of Algeria to identify and characterize sensitive soils susceptible to swelling. This phenomenon poses significant challenges to construction activities and infrastructure development in the area. The study employed a multidisciplinary approach, combining geotechnical and mineralogical analyses to understand the behavior of sensitive soils in the region. Geotechnical investigations involved laboratory identification tests, including Atterberg limits, grain size analysis, methylene blue value, sedimentometry, as well as mechanical tests: oedometer swelling and compressibility tests. Additionally, over 110 boreholes in four sectors were drilled in order to collect soil samples for the analysis. Classification of the studied soils was performed based on grain size distribution, Atterberg limits, and geotechnical properties, utilizing classification systems like LPC and GTR. Results indicated that the sensitive soils in the Tebessa region predominantly belonged to highly plastic clayey categories, exhibiting medium to extremely high swelling potential. Mineralogical analysis through X-ray diffraction provided insights into the composition of the clay fraction, with a focus on identifying swelling clay minerals, such as smectites. The study identified a significant presence of smectites in the soil samples, which are known for their high swelling potential. Integrating geotechnical and mineralogical analyses allows engineers to correlate mineral compositions with soil behaviors such as compaction, consolidation, and shear strength. This correlation predicts how the soil will respond to engineering activities such as construction and slope stability. In the Tebessa region, this integration improves the understanding of clayey soil behavior, aiding informed decisions for sustainable development and resilient infrastructure.

Unsupervised Machine Learning for Data-Driven Rock Mass Classification: Addressing Limitations in Existing Systems Using Drilling Data

AbstractRock mass classification systems are crucial for assessing stability and risk in underground construction globally and guiding support and excavation design. However, these systems, developed primarily in the 1970 s, lack access to modern high-resolution data and advanced statistical techniques, limiting their effectiveness as decision-support systems. We outline these limitations and describe how a data-driven system, based on drilling data, can overcome them. Using statistical information extracted from thousands of MWD-data values in one-meter sections of a tunnel profile, acting as a signature of the rock mass, we demonstrate that well-defined clusters can form a foundational basis for various classification systems. Representation learning was used to reduce the dimensionality of 48-value vectors via a nonlinear manifold learning technique (UMAP) and linear principal component analysis (PCA) to enhance clustering. Unsupervised machine learning methods (HDBSCAN, Agglomerative Clustering, K-means) clustered the data, with hyperparameters optimised through multi-objective Bayesian optimisation. Domain knowledge improved clustering by adding extra features to core MWD-data clusters. We structured and correlated these clusters with physical rock properties, including rock type and quality, and analysed cumulative distributions of key MWD-parameters to determine if clusters meaningfully differentiate rock masses. The ability of MWD data to form distinct rock mass clusters suggests substantial potential for future classification systems using this objective, data-driven methodology, minimising human bias.

Performance evaluation of lime-improved lateritic soil with the addition of pulverised snail shell and sawdust ash for sustainable highway infrastructure

This research investigated the effects of lime, Pulverized snail shell (PSS), and sawdust ash on the mechanical properties of lateritic soil for soil stabilization in construction. The use of this waste materials aligns with the United Nations’ Sustainable Development Goals (SDGs), particularly Goal 12 on responsible consumption and production and Goal 9 on sustainable infrastructure development. Reusing waste materials for soil stabilization supports a circular economy approach, diverting these materials from landfills and promoting their sustainable use as valuable resources. Various tests, including maximum dry density, moisture content, unconfined compressive strength (UCS), triaxial, permeability, compressibility, and California Bearing Ratio (CBR) tests, were conducted on soil samples with different proportions of additives. The results show that the addition of additives reduced maximum dry density and increased moisture content. The sample with 6% lime and 7.5% PSS exhibited the highest UCS of 302 kPa after 28 days of curing, while the untreated sample had a UCS of 121 kPa. Triaxial tests revealed reduced cohesion and increased angle of internal friction with higher additive content. The 6% lime and 7.5% PSS sample displayed the highest shear strength of 60.6 kPa and elastic modulus of 181.8 MPa. Permeability tests demonstrated that the 6% lime and 6% sawdust ash sample had the lowest permeability (6.67 × 10–7 m/s) among the stabilized samples. The untreated soil exhibited high compressibility, whereas the 6% lime and 7.5% PSS sample exhibited the highest resistance to compression and deformation. The untreated soil had a soaked CBR value of 8%, while the 6% lime and 7.5% PSS sample achieved the highest soaked CBR value of 38%, making it suitable as a sub-base material. These findings highlight the effectiveness of lime, PSS, and sawdust ash in enhancing the mechanical properties of lateritic soil and offer valuable insights for soil stabilization in construction of Sustainable Highway Infrastructure.

Design of a multi-epitope vaccine candidate against carrion disease by immunoinformatics approach

Carrion's disease, caused by the bacterium Bartonella bacilliformis, is a serious public health problem in Peru, Ecuador and Colombia. Currently there is no available vaccine against B. bacilliformis. While antibiotics are the standard treatment, resistant strains have been reported, and there is a potential spread of the vector that transmits the bacteria. This study aimed to design a multi-epitope vaccine candidate against the causative agent of Carrion's disease using immunoinformatics tools. Predictions of B-cell epitopes, as well as CD4+ and CD8+T cell epitopes, were performed from the entire proteome of B. bacilliformis KC583 using the most frequent alleles from Peru, Ecuador, Colombia, and worldwide. B-cell epitopes and T-cell nested epitopes from outer membrane and virulence-associated proteins were selected. Epitopes were filtered out based on promiscuity, non-allergenicity, conservation, non-homology and non-toxicity. Two vaccine constructs were assembled using linkers. The tertiary structure of the constructs was predicted, and their stability was evaluated through molecular dynamics simulations. The most stable construct was selected for molecular docking with the TLR4 receptor. This study proposes a vaccine construct evaluated in silico as a potential vaccine candidate against Bartonella bacilliformis.

Effect of High-Stress Levels on the Shear Behavior of Geosynthetic-Reinforced Marine Coral Sands

As an important construction material, the mechanical and deformation properties of marine coral sand determine the safety and stability of related island and coastal engineering construction. The porous and easily broken characteristics of coral sand often make it difficult to meet engineering construction needs. In particular, coral sand undergoes a large amount of particle breakage under high-stress conditions, which in turn negatively affects its mechanical and deformation properties. In this study, the macro- and micro-mechanical behavior of geosynthetic-reinforced coral sand under high confining pressure was investigated and compared with unreinforced cases using the three-dimensional discrete element method (DEM), which was verified by indoor triaxial tests. The results showed that the stress–strain responses of unreinforced and reinforced coral sand under high confining pressure showed completely different trends, i.e., the hardening tendency shown in the reinforced case. Geosynthetic reinforcement can significantly inhibit the stress–strain softening and bulging deformation of coral sand under high confining pressure, thus improving the shear mechanical performance of the reinforced sample. At the microscopic scale, high confining pressure and reinforcement affected the contact force distribution pattern and stress level between particles, determining the macroscopic mechanical and deformation performance. In addition, the breakage of particles under high confining pressure was mainly affected by shear strain and reinforcement. The particle fragment distribution, particle gradation, and relative breakage index exhibited different trends at different confining pressure levels. These breakage characteristics were closely related to the deformation and stress levels of unreinforced and reinforced samples.

Fractional Derivative-based Burger Creep Model for Soft Rocks and its Verification Using Tunnel Monitoring Results and Experimental Data

AbstractConsidering the creep behavior of soft and weak rocks is critical for analyzing the long-term stability of underground constructions. This paper introduces a novel creep constitutive model to characterize the creep behavior of rocks under uniaxial and triaxial stress states. The fractional derivative Abel dashpot was used to improve the Burger model, and a viscoplastic component was added in series with the modified Burgers model to replicate the tertiary phase of rock creep. The effectiveness of the model was verified using creep test data from various soft rocks and monitoring measurements from a tunnel excavated in heavily jointed weak rock masses. Furthermore, a sensitivity analysis was carried out to assess the impact of the model parameters on creep deformation, and a comparative study was performed to evaluate the efficacy of the suggested model in modeling the accelerated stage of rock creep compared with some existing models. The strong agreement observed between the calculated results and both the creep test data and tunnel monitoring measurements underscores the accuracy and validity of the proposed model. The comparative analysis further revealed that the proposed model offers the highest fitting efficiency for describing the tertiary stage of rock creep. These findings suggest that the model effectively captures the creep behavior of rocks and precisely represents the entire creep process.