Stable Construct Research Articles

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.

Relationship between personality and music preference: Psychometric adaptation of the music preference scales in a Chinese sample

Individuals evidently have different tastes in and preferences for music. The purpose of this study was to develop two scales for measuring music preference based on genres (text-based) and excerpts (clip-based), using a Chinese sample to explore the relationship between music preference and personality. Specifically, we collected measures of people’s self-reported preferences for a wide range of music genres for further analysis in Study 1. In Study 2, we developed two music preference scales based on the genres identified in Study 1, one text- and the other clip-based. The results of two principal component analyses suggest three-dimensional psychological structures of music preference using both versions of the scale: (1) Traditional and Retro, (2) Exotic and Complex, and (3) Intense and Rebellious. Correlation and regression analyses of music preferences and personality also indicated that music preference is a relatively stable construct that reflects personality traits. Moreover, the three factors identified from the results of studying music preferences in a Chinese sample differ from those identified in studies of music preference in Western countries, suggesting that music preference is influenced by culture. The two scales yielded similar but slightly different outcomes reflecting their discrete emphases and characteristics; they can be used separately or together, depending on the research topic and question. In this study we verified the structure of music preference among a Chinese sample. It provides a reference point for theoretical research on music preference and personality and has practical applications.

Initial construct stability of long cephalomedullary nails with superior locking for a complex trochanteric fracture model AO31A2.2– a biomechanical study

BackgroundComplex fractures of the trochanteric region, as well as fractures located in the directly subtrochanteric region, are controversially discussed around the world regarding the nail type to be used. A long nail is recommended by manufacturers but requires longer surgical and fluoroscopy times. A possible solution could be a nail with an appropriate length which can be locked in a minimally invasive manner by the main aiming device. We aimed to determine if such a nail model (DCN SL nail, SWEMAC, Linköping, Sweden) offers similar structural stability on biomechanical testing on artificial bone as a standard long nail when used to treat complex trochanteric fractures and compared it to long nails usually used in this setting.MethodsAn osteoporotic bone model was chosen. The Swemac Hansson DCN Nail System was used as osteosynthesis material. Two types of nails were chosen: a superior lock nail which can be implanted with a singular targeting device, and a long nail with distal locking using free-hand technique. AO31A2.2 fractures were simulated in a standardised manner. Axial height of the construct, varus collapse, and rotational deformity directly after nail insertion were simulated. A Universal Testing Machine was used. Measurements were made with a stereo-optic tracking system.FindingsThere was a detectable difference in the axial fracture movement resulting in narrowing of the fracture gap. There was no difference in varus collapse or rotational deformity between the nail variantsConclusionWe conclude that there are small differences which are clinically insignificant and that a superior locking nail can safely be used to manage complex trochanteric fractures.

Leveraging computer-aided design and artificial intelligence to develop a next-generation multi-epitope tuberculosis vaccine candidate

BackgroundTuberculosis (TB) remains a global public health challenge. The existing Bacillus Calmette–Guérin vaccine has limited efficacy in preventing adult pulmonary TB, necessitating the development of new vaccines with improved protective effects. MethodsComputer-aided design and artificial intelligence technologies, combined with bioinformatics and immunoinformatics approaches, were used to design a multi-epitope vaccine (MEV) against TB. Comprehensive bioinformatics analyses were conducted to evaluate the physicochemical properties, spatial structure, immunogenicity, molecular dynamics (MD), and immunological characteristics of the MEV. ResultsWe constructed a MEV, designated ZL12138L, containing 13 helper T lymphocyte epitopes, 12 cytotoxic T lymphocyte epitopes, 8 B-cell epitopes, as well as Toll-like receptor (TLR) agonists and helper peptides. Bioinformatics analyses revealed that ZL12138L should exhibit excellent immunogenicity and antigenicity, with no toxicity or allergenicity, and had potential to induce robust immune responses and high solubility, the immunogenicity score was 4.14449, the antigenicity score was 0.8843, and the immunological score was 0.470. Moreover, ZL12138L showed high population coverage for human leukocyte antigen class I and II alleles, reaching 92.41% and 90.17%, respectively, globally. Molecular docking analysis indicated favorable binding affinity of ZL12138L with TLR-2 and TLR-4, with binding energies of −1173.4 and −1360.5 kcal/mol, respectively. Normal mode analysis and MD simulations indicated the stability and dynamic properties of the vaccine construct. Immune simulation predictions suggested that ZL12138L could effectively activate innate and adaptive immune cells, inducing high levels of Type 1 T helper cell cytokines. ConclusionsThis study provides compelling evidence for ZL12138L as a promising TB vaccine candidate. Future research will focus on experimental validation and further optimization of the vaccine design.

Development and validation of the Forms and Functions of Aggressive Behavior Scale.

Preventing aggression is a global social issue that warrants additional research with up-to-date measures. Aggressive behaviors manifest in several ways, and the proper assessment should capture its multidimensional nature. We developed the Forms and Functions of Aggressive Behavior Scale (FFABS) to capture the field's current multidimensional understanding of aggression, including its forms (physical, verbal, and relational) and functions (proactive and reactive). Across three studies (N = 1388), we validated the factor structure of the FFABS, obtained partial scalar measurement invariance for males and females, and demonstrated consistent patterns with theoretically related stable constructs and with behavioral measures of inhibitory control and aggressive behaviors, establishing convergent and discriminant validity. We discuss the findings, limitations, practical implications, and future research directions.

Research on the Construction Mechanics and Stability Control Technology of Expressway Tunnel Based on Numerical Analysis

As an effective structural form, connecting arch tunnel has been widely used in practical engineering because of its smooth linear shape, small footprint and good bridge and tunnel connection. With the increase of domestic traffic volume year by year, the width of the even arch tunnel is gradually changed from two-way four lanes to two-way six lanes. I20 I-steel, spacing 0.75∼1 m, anchor length 3∼4 m, ring spacing 0.5∼1 m, the side ring spacing of the middle wall is 0.75 m, the side ring spacing of the side wall is 1 m, and the shotcrete thickness is 0.25∼0.3 m. The excavation span of a two-way six-lane continuous-arch tunnel is considerable, leading to complex stress characteristics, thereby posing risks to construction safety and structural stability. Following the construction of the initial tunnel, disturbance to the surrounding rock occurs, affecting subsequent excavation phases. The initial support requirements for subsequent excavations are more intricate, with increased internal forces compared to the initial tunnel segment. As the rear tunnel progresses, the surrounding rock near the middle wall shifts towards the rear tunnel, reducing internal forces in the concrete and steel arch frame. However, as the rear tunnel distance increases, concrete stress and axial forces on the middle wall side of the initial tunnel begin to rise. Throughout the construction, the steel arch frame’s internal forces and spray concrete stress on the middle wall side’s arch waist and foot are the highest, making them susceptible to disruption from construction on the opposite side, thus constituting critical tunnel components. Numerical simulations effectively capture surrounding rock and structural stress dynamics during large-span arch tunnel construction. Simulation outcomes align closely with field measurements, particularly in three-dimensional simulations, enhancing construction understanding and management.

Long-term functional outcomes of BIFOLD osteosynthesis in distal femoral fractures with metaphyseal comminution: A retrospective analysis

BackgroundThis retrospective study aimed to evaluate the long-term functional outcomes of BIFOLD osteosynthesis, employing retrograde nailing and distal femoral locked plating, in patients with distal femoral fractures and metaphyseal comminution. MethodsA retrospective analysis was conducted on patients treated for distal femur fractures with metaphyseal comminution between 2012 and 2022, with a minimum follow-up of 2 years. Inclusion criteria encompassed distal femur fractures with metaphyseal comminution, excluding specific conditions. BIFOLD osteosynthesis was employed in all 33 cases, utilizing retrograde SIGN (Surgical Implant Generation Network Nail) and distal femoral locking plates. Primary outcome measures included radiographic and functional outcomes assessed through the Sanders functional evaluation score, with secondary outcomes focusing on perioperative or postoperative complications. ResultsA total of 33 patients (21 male, 12 female) were included, with an average age of 51.4 years. BIFOLD osteosynthesis exhibited an average radiographic fracture healing time of 6.2 ± 2.5 months. The procedure's average operative time was 100 ± 15 min, and blood loss averaged 420 ± 50 ml. According to Sanders criteria, 28 patients (84.84 %) demonstrated well-to-excellent functional outcomes, while 3 patients (9.09 %) reported fair outcomes, and 2 patients (6.06 %) reported poor outcomes. No significant shortening or implant failure occurred, and all patients achieved over 90 degrees of knee range of motion within 8 weeks. One patient experienced superficial infection, and two patients exhibited insignificant coronal plane deformity. ConclusionBIFOLD osteosynthesis, combining intra and extra medullary fixation principles, offers a stable construct for distal femoral fractures with metaphyseal comminution. This approach facilitates faster ambulation, pain relief, early knee joint mobilization, and significant early union, resulting in improved functional outcomes. Additionally, BIFOLD osteosynthesis helps prevent collapse, translational and rotational deformities, as well as shortening.

Insights into potential of banana leaf powder as a mud soil stabilizer

This study proposes a novel method for managing surplus soil in urban construction projects by investigating the use of banana leaf powder (BLP) as an eco-friendly and efficient mud-soil stabilizer. This study is pioneering in its focus on the use of an agricultural waste product, BLP, as an alternative to conventional methods that frequently rely on cement or lime, which pose environmental concerns owing to their high alkalinity and carbon emissions. BLP, derived from dried and pulverized banana leaves, traditionally used in various industries, was evaluated for its suitability as a stabilizer against orange peel biopolymer (OBP) and fly ash (FA). The findings of this study are groundbreaking. BLP's water absorption capacity, Wab, although lower than that of OBP, was significantly higher than that of FA, demonstrating its potential as a mud soil stabilizer. BLP increased the compaction and strength of the treated clay, whereas OBP made it more challenging to compact the clay owing to gelatinization. The ease of compaction with BLP is attributed to the absorption of free water into the pores of the particles. These results suggest that differences in the stabilizer's water absorption mechanism affect the effectiveness of the post-treatment compaction process on the treated soil. An analysis of the impact of water absorption capacity on the cone index, qc, revealed a material-independent relationship between the parameter β (=Wab × A, where A denotes stabilizer addition content) and qc for BLP and FA. This is because, in contrast to OBP, BLP and FA did not gelatinize the free water that was not absorbed by the stabilizer and remained in the same form within the treated clay. This indicates that understanding the water absorption capacity and mechanism of organic- or inorganic-based stabilizers is important for predicting the strength of treated soil. The same relationship between β and qc holds true for the hybrid-treated clay using both BLP and FA, with β considered to be the sum of β for both BLP and FA. Furthermore, this study innovatively addresses the concern of BLP decay in treated soil by creating a hybrid stabilizer with FA and conducting experiments to accelerate BLP decay using fungal mycelia. These experiments revealed that the hybrid-treated clay exhibited a more gradual decrease in carbon content and stabilized pH levels, implying that FA could inhibit decay by fungal mycelia, improving the BLP-treated soil's long-term durability. These findings suggest that agricultural wastes with high organic content can be effectively used for soil stabilization and ground improvement in civil engineering construction and maintenance projects by combining inorganic materials and taking advantage of their properties, such as high water absorbency. This can address the issues (such as high alkalinity and high carbon dioxide emissions) associated with cement- and lime-based stabilizers, which were previously widely used.

ChebNet: Efficient and Stable Constructions of Deep Neural Networks with Rectified Power Units via Chebyshev Approximation

ChebNet: Efficient and Stable Constructions of Deep Neural Networks with Rectified Power Units via Chebyshev Approximation

Evaluation of long-term stability of L-asparaginase encapsulated PLL-g-PEG nanoparticles in solution to aid in therapeutic delivery

Abstract L-asparaginase (L-ASNase) is a therapeutic enzyme that is widely used for the treatment of hematopoietic diseases such as acute lymphoblastic leukemia and lymphomas. L-ASNase destroys asparagine dependent tumors by degrading circulating L-asparagine and thereby destroying malignant cells. As a protein drug, L-ASNase carries a few inherent drawbacks including short circulating half-life, low stability, and low catalytic activity under physiological conditions. Moreover, due to the bacterial origin of L-ASNase used in treatments, there have been reports with high frequency of hypersensitivity reactions in patients. The use of this drug in adult cancer populations has largely been hindered not only due to its immunological side effects but also due to non-immunogenic toxicities such as pancreatitis, liver toxicities, coagulopathy, and neurotoxicity. Therefore, it is vital to find new methods to decrease its immunogenic/toxicity profile while increasing the stability and half-life. The purpose of this study is to achieve a new L-ASNase polymer nanocarrier to improve stability of the enzyme while masking it from the immune system of the host. We designed and characterized a nanoparticle (NP) where a poly-L-lysine-grafted-poly(ethylene) glycol co-polymer was used to encapsulate L-ASNase. The primary focus of the study was to evaluate the stability and encapsulation efficiency of this NP construct over time. There was no aggregation of NPs observed during the study period of 6 months in solution and NPs had a 0.436 mV surface charge. L-ASNase NPs showed a percent asparaginase activity of 31% compared to free L-ASNase. Under physiological conditions NPs were found to be intact and retained the encapsulated proteins for up to 6 months in solution. Together, these results demonstrate that L-ASNase loaded PLL-g-PEG NPs may serve as a fundamental platform to design nanocarriers to prolong stability in solution.

A Strain-Controlled Finite Strain Model for CRD Consolidation of Saturated Clays Considering Non-Linear Compression and Permeability Relationships

Consolidation is the combined phenomenon of the compression and groundwater seepage of clay. Accurate evaluation of the consolidation characteristic is essential for the design, construction, and long-term stability of geotechnical structures. In this study, a strain-controlled non-linear finite strain model for constant rate-of-deformation (CRD) consolidation was developed for quickly and reliably predicting the consolidation behavior of clay soils. The model can account for any form of non-linear compression and permeability relationships, thus considering variations in the coefficient of consolidation. Being strain-controlled, it overcomes the limitations of stress-controlled models which require complex numerical iteration. The validity and accuracy of this model were verified through rigorous comparisons with both numerical simulations and experimental data. For normally consolidated soils, a non-linear e-lgσ′compression model was used instead of a linear compression model. For overconsolidated soils, the Harris function compression model was determined to be recommended to overcome the discontinuities in total stress and pore pressure caused by the traditional piecewise e-lgσ′ model. It was also found that determining the steady state of consolidation for normally consolidated soils should use the non-linear method, while the linear method is suggested to be adopted for overconsolidated soils.

Seismic Performance and Construction Stability of Long- Span Continuous Rigid-Frame Bridges with Tall Piers

Seismic Performance and Construction Stability of Long- Span Continuous Rigid-Frame Bridges with Tall Piers

Machine learning tools used for mapping some immunogenic epitopes within the major structural proteins of the bovine coronavirus (BCoV) and for the in silico design of the multiepitope-based vaccines.

BCoV is one of the significant causes of enteritis in young calves; it may also be responsible for many respiratory outbreaks in young calves. BCoV participates in the development of bovine respiratory disease complex in association with other bacterial pathogens. Our study aimed (1) to map the immunogenic epitopes (B and T cells) within the major BCoV structural proteins. These epitopes are believed to induce a robust immune response through the interaction with major histocompatibility complex (MHC class II) molecules (2) to design some novel BCoV multiepitope-based vaccines. The goal is achieved through several integrated in silico prediction computational tools to map these epitopes within the major BCoV structural proteins. The final vaccine was constructed in conjugation with the Choleratoxin B toxin as an adjuvant. The tertiary structure of each vaccine construct was modeled through the AlphaFold2 tools. The constructed vaccine was linked to some immunostimulants such as Toll-like receptors (TLR2 and TLR4). We also predicted the affinity binding of these vaccines with this targeted protein using molecular docking. The stability and purity of each vaccine construct were assessed using the Ramachandran plot and the Z-score values. We created the in silico cloning vaccine constructs using various expression vectors through vector builder and Snap gene. The average range of major BCoV structural proteins was detected within the range of 0.4 to 0.5, which confirmed their antigen and allergic properties. The binding energy values were detected between -7.9 and -9.4 eV and also confirmed their best interaction between our vaccine construct and Toll-like receptors. Our in silico cloning method expedited the creation of vaccine constructs and established a strong basis for upcoming clinical trials and experimental validations. Our designed multiepitope vaccine candidates per each BCoV structural protein showed high antigenicity, immunogenicity, non-allergic, non-toxic, and high-water solubility. Further studies are highly encouraged to validate the efficacy of these novel BCoV vaccines in the natural host.

Double-crosslinked dECM bioink to print a self-sustaining 3D multi-layered aortic-like construct

Cardiovascular disease is the leading cause of death worldwide, with related mortality increasing from 12.1 million to 18.6 million in the past 30 years.To address the supply limitation of autologous vascular grafts and overcome the limits of current treatment options, 3D bioprinting techniques have been investigated.This study aimed at introducing a self-supporting and multi-layered 3D bioprinted construct as a promising alternative for large-blood vessel replacement. To this end, we developed an alginate-gelatin bioink enriched with decellularized extracellular matrix (dECM) of porcine aorta combined with a two-step crosslinking process. We investigated the feasibility of achieving structural stability and shape fidelity of the bioprinted construct over time through rheological characterization, printability tests, and degradation tests.According to the results of rheology and printability tests, dECM-enriched bioink combined with the double-crosslinking process (internal and external crosslink) showed good printability and high shape fidelity, withstanding more than 35 layers without the need for support. Moreover, the bioprinted construct preserved its structural stability over time, retaining a wall thickness comparable to that of the native aorta. Finally, immortalized mouse fibroblasts embedded in the bioink were well adhered to the bioink and alive over time. The double-crosslinked bioink represents an impactful strategy to produce an alternative conduit with the native hierarchical structure of the large blood vessels.

Utilization of calcium carbide residue based soil stabilizer in road construction: Strength, environmental impact, and field application

This research paper delves into the utilization of calcium carbide residue (CCR)based stabilizer (designated as CSC) in road subgrade soil stabilization, with a comprehensive evaluation of its mechanical strength, environmental safety, and efficacy in field applications. Amid growing environmental concerns and the push for sustainable construction materials, this study presents an innovative approach by repurposing CCR, a by-product of the acetylene production process, in enhancing the structural integrity of road foundations. Through a series of laboratory tests, the investigation reveals significant improvements in the unconfined compressive strength (UCS) and California bearing ratio (CBR) of CSC-stabilized soils, compared to traditional lime stabilization methods. The field test DCPI results indicate that the CBR value of the field test CSC stabilised soil is 50.19% after three days, whereas the CBR value of the field test lime stabilised soil is only 29.51% after the same period. The CBR value of the CSC stabilised soil is significantly higher than that of the lime stabilised soil. This study also tested the leachate of the stabilised soil, analysing the concentration of heavy metals. The results indicated that the leachate from the stabilised soil complies with heavy metal leaching standards, demonstrating the ecological benefits of CSC utilisation. Furthermore, field experiments conducted on the G312 National Highway in Jiangsu Province, China, further validated the laboratory test results. The findings from the field trials indicated that sections stabilised with CSC exhibited superior performance in terms of reduced soil deformation and enhanced load-bearing capacity. Additionally, a life cycle carbon emission analysis was conducted for the field trial section, comparing the carbon emissions of the CSC binder with those of the lime binder throughout the entire life cycle of road construction. The results from the trial section demonstrated that the use of the CSC binder significantly reduced carbon emissions. The study underscores the potential of CSC as a cost-effective, environmentally friendly stabilizing agent, offering a pragmatic solution to the dual challenges of industrial waste management and soil stabilization in road construction.

Experimental study on the macroscopic and mesoscopic mechanical characteristics of deep damaged and fractured rock

Most of the rock surrounding deep roadways is in a fractured state; fractured rock has significant rheological properties, and the time-dependent mechanical properties of fractured rock affect excavation construction, support design, and long-term stability of deep roadways. Triaxial compression and mercury intrusion tests are conducted on the bearing characteristics of severely damaged and fractured rock samples, indicating the strength degradation properties of these samples. The evolution of the internal pore structure in damaged and fractured rock samples is analyzed in relation to changes in unloading points (pre-peak stage, peak point, and post-peak stage), leading to the establishment of a quantitative evaluation index for rock damage based on the porosity evolution. Short-term rheological testing is performed on rock samples with varying degrees of damage and fracture, demonstrating the evolution of creep and stress relaxation characteristics. The findings contribute to a deeper theoretical understanding of the post-peak mechanical properties of coal and rock masses, which hold significant theoretical implications and can inform research on long-term stability in underground engineering applications, such as deeply buried roadways, tunnels, and chambers.

[Artículo traducido] Consejos y trucos para el uso de cemento óseo en tornillos pediculares y en reemplazos de cuerpos vertebrales: una revisión de la literatura respaldada por dos informes de casos

BackgroundThe prevalence of osteoporosis is escalating alongside an aging global population, increasing the demand for spinal surgeries, including those necessitating cement augmentation for enhanced construct stability. ObjectiveThis article delves into the nuanced application of cement augmentation techniques for pedicle screws and vertebral body replacements (VBR), aimed at optimizing surgical outcomes in osteoporotic spines. MethodDrawing from a comprehensive literature review according to important clinical and biomechanical studies and the authors’ clinical experiences, we elucidate strategies to mitigate complications and improve surgical efficacy. ResultsCement augmentation has shown promise in managing vertebral fractures and in securing pedicle screws within osteoporotic vertebrae, with the advent of polymethylmethacrylate (PMMA) bone cement marking a pivotal advancement in spinal surgery. We highlight intraoperative measures like the choice between pre-injecting cement and utilizing cannulated or fenestrated screws, emphasizing the importance of controlling cement viscosity to prevent leakage and embolism. Through two case reports, we demonstrate the practical application of endplate cementation following VBR. ConclusionWhile the use of cement augmentation poses certain risks, its judicious application—supported by evidence-based guidelines and surgical expertise—can substantially enhance the stability of spinal constructs in osteoporotic patients. This allows a reduction in instrumentation length by enhancing biomechanical stability concerning pullout, bending, and rotational forces. Furthermore, the incidence of endplate sintering following VBF can be significantly reduced. Future research, particularly on antibiotic-loaded PMMA, may further expand its utility and optimize its safety profile.

Resilience Assessment of Deep Excavation Engineering Systems Based on Bayesian Network

As a key component of infrastructure, the construction safety of deep excavation is particularly important. In order to improve the safety and stability of Deep excavation construction, research on the risk resistance and rapid recovery capabilities of Deep excavation projects is carried out. By introducing the concept of resilience, we analyze the key factors that affect the safety and resilience of Deep excavation projects, use Bayesian networks to establish a resilience model that expresses the causal relationship between factors, and learn the parameters of the network model through data samples collected through surveys; by adjusting the network Analyze the relationship between each factor and system resilience at each node, and clarify the measures that should be taken and key control objects, thereby improving the system resilience and ensuring that normal construction can be carried out safely and orderly. Research shows that this model can be used to quantify the safety toughness value of deep excavation and reason and analyze the impact of various factors on the toughness value, thereby improving risk management and decision support capabilities.

Mechanical and Biological Characterization of Ionic and Photo-Crosslinking Effects on Gelatin-Based Hydrogel for Cartilage Tissue Engineering Applications.

Articular cartilage degeneration poses a significant public health challenge; techniques such as 3D bioprinting are being explored for its regeneration in vitro. Gelatin-based hydrogels represent one of the most promising biopolymers used in cartilage tissue engineering, especially for its collagen composition and tunable mechanical properties. However, there are no standard protocols that define process parameters such as the crosslinking method to apply. To this aim, a reproducible study was conducted for exploring the influence of different crosslinking methods on 3D bioprinted gelatin structures. This study assessed mechanical properties and cell viability in relation to various crosslinking techniques, revealing promising results particularly for dual (photo + ionic) crosslinking methods, which achieved high cell viability and tunable stiffness. These findings offer new insights into the effects of crosslinking methods on 3D bioprinted gelatin for cartilage applications. For example, ionic and photo-crosslinking methods provide softer materials, with photo-crosslinking supporting cell stretching and diffusion, while ionic crosslinking preserves a spherical stem cell morphology. On the other hand, dual crosslinking provides a stiffer, optimized solution for creating stable cartilage-like constructs. The results of this study offer a new perspective on the standardization of gelatin for cartilage bioprinting, bridging the gap between research and clinical applications.

Does Sagittal Alignment Matter? A Biomechanical Look at Pinning Pediatric Supracondylar Humerus Fractures.

Closed manipulation and percutaneous pinning is standard of care for displaced supracondylar humerus fractures, yet the optimal pin configuration, particularly in the sagittal plane, is not well defined. This study evaluates how sagittal plane pin variations affect construct strength biomechanically. One hundred synthetic pediatric humerus models were used to emulate supracondylar humerus fracture. The models were pinned using 4 different configurations uniformly divergent in the coronal plane with variations in the sagittal plane: (1) 2 diverging pins with the lateral pin anterior (n = 25), (2) 2 diverging pins with the lateral pin posterior (n = 25), (3) 2 parallel pins (n = 25), and (4) 3 parallel pins (n = 25). The models were tested under bending (flexion, extension, and varus) and rotational (internal and external) forces, measuring stiffness and torque. Statistical analyses identified significant differences across configurations. The 2-pin parallel configuration (9.68N/mm in extension, 8.76N/mm in flexion, 0.14 N-m/deg in internal rotation, and 0.14 N-m/deg in external rotation) performed similarly to the 3-pin parallel setup (10.77N/mm in extension, 7.78N/mm in flexion, 0.16 N-m/deg in internal rotation, and 0.14 N-m/deg in external rotation), with no significant differences in stiffness. In contrast, both parallel configurations significantly outperformed the 2-pin anterior (5.22N/mm in extension, 5.7N/mm in flexion, 0.11 N-m/deg in internal rotation and 0.10 N-m/deg in external rotation) and posterior (9.86N/mm in extension, 8.31N/mm in flexion, 0.12N-m/deg in internal rotation, and 0.11 N-m/deg in external rotation) configurations in resisting deformation. No notable disparities were observed in varus loading among any configurations. This study illuminates the sagittal plane's role in construct stability. It suggests that, when utilizing 2-pins, parallel configurations in the sagittal plane improve biomechanical stability. In addition, it suggests avoiding the lateral anterior pin configuration due to its biomechanical inferiority. Further research should assess ultimate strength and compare various 3-pin configurations to better delineate differences between 2-pin and 3-pin configurations regarding sagittal plane alignment. Level III-biomechanical study.