RESUMEN
The unsuitable deformation stimulus, harsh urine environment, and lack of a regenerative microenvironment (RME) prevent scaffold-based urethral repair and ultimately lead to irreversible urethral scarring. The researchers clarify the optimal elastic modulus of the urethral scaffolds for urethral repair and design a multilayered PVA hydrogel scaffold for urethral scar-free healing. The inner layer of the scaffold has self-healing properties, which ensures that the wound effectively resists harsh urine erosion, even when subjected to sutures. In addition, the scaffold's outer layer has an extracellular matrix-like structure that synergizes with adipose-derived stem cells to create a favorable RME. In vivo experiments confirm successful urethral scar-free healing using the PVA multilayered hydrogel scaffold. Further mechanistic study shows that the PVA multilayer hydrogel effectively resists the urine-induced inflammatory response and accelerates the transition of urethral wound healing to the proliferative phase by regulating macrophage polarization, thus providing favorable conditions for urethral scar-free healing. This study provides mechanical criteria for the fabrication of urethral tissue-engineered scaffolds, as well as important insights into their design.
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Módulo de Elasticidad , Hidrogeles , Andamios del Tejido , Uretra , Cicatrización de Heridas , Andamios del Tejido/química , Animales , Hidrogeles/química , Ingeniería de Tejidos/métodos , Ratones , Regeneración , Cicatriz/patología , Masculino , Microambiente Celular , Ratas Sprague-Dawley , Células Madre/citologíaRESUMEN
The fabrication of multi-component film with colloidal particles could be inconvenient. A novel "swell-permeate" (SP) strategy was proposed to form homogeneous multi-component films. The SP strategy allows colloidal particles to fit into the polymer network by stretching the polymer chains assisted by water. We demonstrated the strategy by creating films with polysaccharide substrates as ß-cyclodextrin grafted chitosan (CS) with nanocellulose. The addition of nanocellulose significantly increased the mechanical properties and the barrier performance of the films. The size of nanocellulose particles in affecting mechanical properties was investigated by applying different length of cellulose nanocrystal (CNC), the longer of which, due to denser physical entanglements, showed a better increase to the film in the elastic modulus and tensile strength to 4.54-fold and 5.71-fold, respectively. The films were also loaded with ethyl-p-coumarate (EpCA) and had an enhanced performance in anti-microbial for Altenaria alternata, Salmonella typhi, and Escherichia coli. The anti-oxidative property was increased as well, and both effects were valid both in vitro and in ready-to-eat apples. The strategy provides a practical and convenient method for fabricating colloidal particle containing films, and the novel idea of "swell-permeate" is potentially regarded as a new solution to the challenge of ready-to-eat food quality maintenance.
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Celulosa , Quitosano , Escherichia coli , Embalaje de Alimentos , Nanopartículas , Resistencia a la Tracción , Quitosano/química , Celulosa/química , Escherichia coli/efectos de los fármacos , Nanopartículas/química , Antibacterianos/química , Antibacterianos/farmacología , Antioxidantes/química , Antioxidantes/farmacología , beta-Ciclodextrinas/química , Películas Comestibles , Salmonella typhi/efectos de los fármacos , Módulo de ElasticidadRESUMEN
Hydrogel is a kind of degradable hydrophilic polymer, but excessive hydrophilicity leads to larger volume, lower elastic modulus and looser structure, which further affect its use. Especially in the field of biomedical engineering, excessive swelling of the hydrogel can compress the nerves and improve degradation rate resulting in mismatch of tissue growth and released ions. Therefore, anti-swelling hydrogel has been a research hotspot in recent years. This paper reviews the recent research progress on anti-swelling hydrogel, and expounds the application mechanism and preparation method of hydrogel in biomedical engineering, aiming to provide some references for researchers in the field of anti-swelling hydrogel.
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Materiales Biocompatibles , Hidrogeles , Hidrogeles/química , Materiales Biocompatibles/química , Ingeniería de Tejidos/métodos , Ingeniería Biomédica , Interacciones Hidrofóbicas e Hidrofílicas , Polímeros/química , Módulo de Elasticidad , HumanosRESUMEN
Hydrogels are highly sought-after absorbent materials for absorbent pads; however, it is still challenging to achieve a satisfactory balance between mechanical performance, water absorption capacity, and active functionalities. In this work, we presented double-network hydrogels synthesized through acrylic acid (AA) polymerization in the presence of quaternized cellulose nanofibrils (QCNF) and Fe3+. Spectroscopic and microscopic analyses revealed that the combined QCNF and Fe3+ facilitated the formation of double-network hydrogels with combined chemical and physical crosslinking. The synergistic effect of QCNF and Fe3+ resulted in impressive mechanical properties, including tensile strength of 1.98 MPa, fracture elongation of 838.8 %, toughness of 7.47 MJ m-3, and elastic modulus of 0.35 MPa. In comparison to the single-network PAA hydrogel, the PAA/QCNF/Fe3+ (PQFe) hydrogels showed higher and relatively stable swelling ratios under varying pH levels and saline conditions. The PQFe hydrogels exhibited notable antioxidant activity, as evidenced by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, and demonstrated effective antibacterial activity against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). These hydrogels show promising potential as an absorbent interlayer in absorbent pads for active food packaging.
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Resinas Acrílicas , Antibacterianos , Celulosa , Escherichia coli , Hidrogeles , Hierro , Nanofibras , Staphylococcus aureus , Resistencia a la Tracción , Hidrogeles/química , Hidrogeles/farmacología , Celulosa/química , Staphylococcus aureus/efectos de los fármacos , Resinas Acrílicas/química , Escherichia coli/efectos de los fármacos , Nanofibras/química , Hierro/química , Antibacterianos/farmacología , Antibacterianos/química , Antioxidantes/química , Antioxidantes/farmacología , Módulo de ElasticidadRESUMEN
This study examines the corrosion characteristics of weakly cemented sandstone under alkaline conditions, evaluating the effects of varying pH levels on its macroscopic degradation, micro-porosity, and mechanical properties, notably uniaxial compressive strength. Findings reveal that heightened alkalinity exacerbates rock damage, although a temporary alleviation in mass loss occurs between pH 9 and 11 due to pore clogging by complexes formed from cations like Ca2+ and Mg2+.Increased alkalinity induces marked changes in pore features, with an observed rise in pore numbers, transformation of pore shapes from elongated to more spherical, and adjustments in porosity, pore size, and roundness. Furthermore, the study confirms a decline in both the rock's compressive strength and elastic modulus as pH rises. These revelations shed light on the role of pH in the corrosion behavior of weakly cemented sandstone under alkaline conditions, providing a fresh perspective for understanding its corrosion mechanisms in such environments.
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Fuerza Compresiva , Corrosión , Concentración de Iones de Hidrógeno , Porosidad , Soluciones , Álcalis/química , Módulo de ElasticidadRESUMEN
Conductive hydrogels have been widely used in soft robotics, as well as skin-attached and implantable bioelectronic devices. Among the candidates of conductive fillers, conductive polymers have become popular due to their intrinsic conductivity, high biocompatibility, and mechanical flexibility. However, it is still a challenge to construct conductive polymer-incorporated hydrogels with a good performance using a facile method. Herein, we present a simple method for the one-pot preparation of conductive polymer-incorporated hydrogels involving rapid photocuring of the hydrogel template followed by slow in situ polymerization of pyrrole. Due to the use of a milder oxidant, hydrogen peroxide, for polypyrrole synthesis, the photocuring of the hydrogel template and the growing of polypyrrole proceeded in an orderly manner, making it possible to prepare conductive polymer-incorporated hydrogels in one pot. The preparation process is facile and extensible. Moreover, the obtained hydrogels exhibit a series of properties suitable for biomedical strain sensors, including good conductivity (2.49 mS/cm), high stretchability (>200%), and a low Young's modulus (~30 kPa) that is compatible with human skin.
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Conductividad Eléctrica , Hidrogeles , Polímeros , Pirroles , Pirroles/química , Hidrogeles/química , Polímeros/química , Humanos , Técnicas Biosensibles/métodos , Módulo de Elasticidad , Movimiento (Física) , Peróxido de Hidrógeno/químicaRESUMEN
Recently, interest in tooth-colored fluoride-releasing dental materials has increased. Although physical and mechanical properties such as surface hardness, elastic modulus and surface roughness of the restorative materials have been investigated, the effect of different immersion media on these properties is still controversial. The aim of this study was to evaluate the nanohardness, elastic modulus and surface roughness of the fluoride release of tooth-colored restorative materials after immersion in acidic beverages. Prepared samples of three restorative materials (a highly viscous glass ionomer (EQUIA Forte; GC, Tokyo, Japan), a compomer (Dyract XP; Dentsply, Weybridge, UK), and a bioactive restorative material (Activa BioACTIVE; Pulpdent, MA, USA)) were randomly divided and immersed in distilled water, a cola and an orange juice for one week. The HYSITRON T1 950 TriboIndenter device (Hysitron, USA) with the Berkovich diamond indenter tip was used for all measurements. The nanohardness and elastic modulus of the samples were measured by applying a force of 6000 µN to five different points on the sample surface. Surface roughness measurements were evaluated on random samples by scanning five random 40 × 40 µm areas. The properties were measured at the initial and one week after immersion. The values of nanohardness, elastic modulus and surface roughness were tested for significant differences using a two-way analysis of variance (ANOVA) with repeated measures (p < 0.05). Tukey's honest significant difference (HSD) test was used for multiple comparisons. AB (Activa BioACTIVE) had the highest initial mean values for nanohardness. After post-immersion, the highest mean value for elastic modulus was the initial AB value. The lowest mean value for roughness of 100.36 nm was obtained for the initial DX (Dyract XP) measurement. Acidic beverages had a negative effect on the nanohardness, elastic modulus and surface roughness of the restorative materials.
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Bebidas Gaseosas , Módulo de Elasticidad , Fluoruros , Dureza , Ensayo de Materiales , Propiedades de Superficie , Fluoruros/química , Compómeros/química , Humanos , Materiales Dentales/química , Jugos de Frutas y Vegetales , Resinas Acrílicas/química , Restauración Dental Permanente/métodos , Agua/química , Cariostáticos/química , Cementos de Ionómero Vítreo/química , Citrus sinensis/química , Inmersión , Resinas Compuestas/química , Dióxido de SilicioRESUMEN
Hydrogels with sustained lubrication, high load-bearing capacity, and wear resistance are essential for applications in soft tissue replacements and soft material devices. Traditional tough or lubricious hydrogels fail to balance the lubrication and load-bearing functions. Inspired by the gradient-ordered multilayer structures of natural tissues (such as cartilage and ligaments), a tough, smooth, low-permeability, and low-friction anisotropic layered electrospun fiber membrane-reinforced hydrogel was developed using electrospinning and annealing recrystallization. This hydrogel features a stratified porous network structure of varying sizes with tightly bonded interfaces, achieving an interfacial bonding toughness of 1.6 × 103 J/m2. The anisotropic fiber membranes, mimicking the orderly fiber structures within soft tissues, significantly enhance the mechanical properties of the hydrogel with a fracture strength of 20.95 MPa, a Young's modulus of 29.64 MPa, and a tear toughness of 37.94 kJ/m2 and reduce its permeability coefficient (6.1 × 10-17 m4 N-1 s-1). Meanwhile, the hydrogel demonstrates excellent solid-liquid phase load-bearing characteristics, which can markedly improve the tribological performance. Under a contact load of 4.1 MPa, the anisotropic fiber membrane-reinforced hydrogel achieves a friction coefficient of 0.036, a 219% reduction compared with pure hydrogels. Thus, the superior load-bearing and lubricating properties of this layered hydrogel underscore its potential applications in soft tissue replacements, medical implants, and other biomedical devices.
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Hidrogeles , Permeabilidad , Hidrogeles/química , Anisotropía , Materiales Biocompatibles/química , Ensayo de Materiales , Membranas Artificiales , Módulo de Elasticidad , HumanosRESUMEN
The mechanical properties of the sclera play a critical role in supporting the ocular structure and maintaining its shape. However, non-invasive measurements to quantify scleral biomechanics remain challenging. Recently introduced multi-directional optical coherence elastography (OCE) combined with an air-coupled ultrasound transducer for excitation of elastic surface waves was used to estimate phase speed and shear modulus in ex vivo rabbit globes (n = 7). The scleral phase speed (12.1 ± 3.2 m/s) was directional-dependent and higher than for corneal tissue (5.9 ± 1.4 m/s). In the tested locations, the sclera proved to be more anisotropic than the cornea by a factor of 11 in the maximum of modified planar anisotropy coefficient. The scleral shear moduli, estimated using a modified Rayleigh-Lamb wave model, showed significantly higher values in the circumferential direction (65.4 ± 31.9 kPa) than in meridional (22.5 ± 7.2 kPa); and in the anterior zone (27.3 ± 9.3 kPa) than in the posterior zone (17.8 ± 7.4 kPa). The multi-directional scanning approach allowed both quantification and radial mapping of estimated parameters within a single measurement. The results indicate that multi-directional OCE provides a valuable non-invasive assessment of scleral tissue properties that may be useful in the development of improved ocular models, the evaluation of potential myopia treatment strategies, and disease characterization and monitoring.
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Diagnóstico por Imagen de Elasticidad , Esclerótica , Tomografía de Coherencia Óptica , Animales , Conejos , Esclerótica/diagnóstico por imagen , Esclerótica/fisiología , Diagnóstico por Imagen de Elasticidad/métodos , Tomografía de Coherencia Óptica/métodos , Fenómenos Biomecánicos , Córnea/diagnóstico por imagen , Córnea/fisiología , Módulo de ElasticidadRESUMEN
Purpose: The primary objective of the conducted research was to develop an urological stent design for the treatment of male ure-thral stenosis. Given the variable loading conditions inside the urethra, the proposed stent should maintain normal tissue kinetics and obstruct the narrowed lumen. The suitable selection for the stent material significantly influences the regeneration and proper remodeling of the urethral tissues. Methods: In this work, the mechanical characteristics of some polymer materials were studied, including: polydi-oxanone (PDO) and poly(L-lactide) (PLLA)/polycaprolactone (PCL) composite. The obtained mechanical properties for static tensile testing of the materials, allowed the determination of such parameters as Young's modulus (E), tensile strength (R m) and yield strength (R e). Subsequently, the design of a urological stent was developed, for which a numerical analysis was carried out to check the behaviour of the stent during varying loads prevailing in the urethra. Result: The research indicated that PDO has better mechanical properties than the proposed PLLA/PCL composite. The numerical analysis results suggested that the developed stent design can be successfully used in the treatment of male urethral stenosis. The obtained stress and strain distributions in the numerical analysis confirm that the PDO material can be used as a material for an urological stent. Conclusions: The biodegradable polymers can be successfully used in urology. Their advantages over solid materials are their physicochemical properties, the ability to manipulate the rate and time of degradation and the easy availability of materials and manufacturing technology.
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Poliésteres , Stents , Estrechez Uretral , Masculino , Poliésteres/química , Poliésteres/farmacología , Humanos , Estrechez Uretral/fisiopatología , Estrechez Uretral/terapia , Ensayo de Materiales , Resistencia a la Tracción/efectos de los fármacos , Polímeros/química , Polidioxanona/química , Polidioxanona/farmacología , Módulo de ElasticidadRESUMEN
Ultraviolet (UV) light poses a significant threat to human health. Here, we propose a click preparation strategy for creating biomass-based poly(urethane thioether) networks for UV-shielding goggles designed to potentially protect the eyes from UV damage. Eugenol-based diurethanes (EDUs) were synthesized first, and then cross-linked networks were prepared through thiol-ene photoclick chemistry. The obtained high-strength and toughness eugenol-based poly(urethane thioether) networks (EUTNs) show a Young's modulus of 2.6 GPa, a tensile strength of 85 MPa, and a fracture elongation of 2066%. Meanwhile, EUTNs show shape memory behaviors and good optical properties. The EUTN films exhibit transparency while effectively filtering out approximately 99% of UVB and UVC radiation without any UV absorbers added. UV goggles can be integrally fabricated with both lenses and frames made entirely of the same EUTN material. What is more, goggles can be recovered to their original thin film form when not in use.
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Eugenol , Poliuretanos , Rayos Ultravioleta , Poliuretanos/química , Eugenol/química , Resistencia a la Tracción , Módulo de Elasticidad , HumanosRESUMEN
Regenerative medicine is continuously looking for new natural, biocompatible and possibly biodegradable materials, but also mechanically compliant. Chitosan is emerging as a promising FDA-approved biopolymer for tissue engineering, however, its exploitation in regenerative devices is limited by its brittleness and can be further improved, for example by blending it with other materials or by tuning its superficial microstructure. Here, we developed membranes made of chitosan (Chi) and glycerol, by solvent casting, and micro-patterned them with directional geometries having different levels of axial symmetry. These membranes were characterized by light microscopies, atomic force microscopy (AFM), by thermal, mechanical and degradation assays, and also testedin vitroas scaffolds with Schwann cells (SCs). The glycerol-blended Chi membranes are optimized in terms of mechanical properties, and present a physiological-grade Young's modulus (≈0.7 MPa). The directional topographies are effective in directing cell polarization and migration and in particular are highly performant substrates for collective cell migration. Here, we demonstrate that a combination of a soft compliant biomaterial and a topographical micropatterning can improve the integration of these scaffolds with SCs, a fundamental step in the peripheral nerve regeneration process.
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Materiales Biocompatibles , Movimiento Celular , Quitosano , Módulo de Elasticidad , Glicerol , Regeneración Nerviosa , Células de Schwann , Ingeniería de Tejidos , Andamios del Tejido , Cicatrización de Heridas , Quitosano/química , Células de Schwann/citología , Glicerol/química , Animales , Materiales Biocompatibles/química , Andamios del Tejido/química , Ratas , Ingeniería de Tejidos/métodos , Microscopía de Fuerza Atómica , Ensayo de Materiales , Membranas Artificiales , Medicina Regenerativa/métodosRESUMEN
BACKGROUND: Intraarticular hip pain represents a substantial clinical challenge, with recent studies implicating lesions in the ligamentum teres as potential contributors. Even more so, damage to the ligamentum teres is particularly prevalent among young patients undergoing joint-preserving interventions. Although several studies have investigated the biomechanical attributes of the ligamentum teres, inconsistencies in reported findings and reliance on cadaveric or animal models have raised concerns regarding the extrapolation of results to clinical practice. Furthermore, there is a lack of research examining ligamentum teres biomechanics specifically within the relevant patient cohort-individuals who benefit from joint-preserving surgical interventions. QUESTIONS/PURPOSES: We sought (1) to determine the biomechanical properties (ultimate load to failure, tensile strength, stiffness, and elastic modulus) of fresh-frozen ligaments from patients undergoing surgical hip dislocation, and (2) to identify patient-specific factors that are associated with them. METHODS: This was an institutional review board-approved study on intraoperatively harvested ligamentum teres from 74 consecutive patients undergoing surgical hip dislocation for joint preservation (August 2021 to September 2022). After the exclusion of patients with previous surgery, posttraumatic deformities, avascular necrosis, slipped capital femoral epiphysis, and Perthes disease, 31 ligaments from 31 patients were analyzed. The mean age of the study group was 27 ± 8 years, and 61% (19) of participants were male. The main indication for surgery was femoroacetabular impingement. Standardized AP pelvic and axial radiographs and CT scans were performed in all patients for better radiological description of the population and to identify associated radiological factors. The ligament was thoroughly transected at its origin on the fossa acetabuli and at the insertion area on the fovea capitis and stored at -20°C until utilization. Specimens were mounted to a materials testing machine via custom clamps that minimized slippage and the likelihood of failure at the clamp. Force-displacement and stress-strain curves were generated. Ultimate failure load (N), tensile strength (MPa), stiffness (N/mm), and elastic modulus (MPa) were determined. Using a multivariate regression analysis and a subgroup analysis, we tested demographic, degenerative, and radiographic factors as potential associated factors. RESULTS: The ligamentum teres demonstrated an ultimate load to failure of 126 ± 92 N, and the tensile strength was 1 ± 1 MPa. The ligaments exhibited a stiffness of 24 ± 15 N/mm and an elastic modulus of 7 ± 5 MPa. After controlling for potential confounding variables like age, fossa/fovea degeneration, and acetabular/femoral morphologies, we found that female sex was an independent factor for higher tensile strength, stiffness, and elastic modulus. Excessive femoral version was independently associated with lower load to failure (HR 122 [95% CI 47 to 197]) and stiffness (HR 15 [95% CI 2 to 27]). Damage to the acetabular fossa was associated with reduced load to failure (HR -93 [95% CI -159 to -27]). CONCLUSION: Overall, the ligamentum teres is a relatively weak ligament. Sex, degeneration, and excessive femoral version are influencing factors on strength of the ligamentum teres. The ligamentum teres exhibits lower strength compared with other joint-stabilizing ligaments, which calls into question its overall contribution to hip stability. CLINICAL RELEVANCE: Young patients undergoing hip-preserving surgery are the population at risk for ligamentum teres lesions. Baseline values for load to failure, tensile strength, elastic modulus, and stiffness are needed to better understand those lesions in this cohort of interest.
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Articulación de la Cadera , Humanos , Masculino , Femenino , Fenómenos Biomecánicos , Adulto , Adulto Joven , Articulación de la Cadera/cirugía , Articulación de la Cadera/fisiopatología , Articulación de la Cadera/diagnóstico por imagen , Luxación de la Cadera/fisiopatología , Luxación de la Cadera/cirugía , Luxación de la Cadera/diagnóstico por imagen , Ligamentos Articulares/fisiopatología , Ligamentos Articulares/cirugía , Ligamentos Articulares/diagnóstico por imagen , Ligamentos Redondos/cirugía , Ligamentos Redondos/fisiopatología , Resistencia a la Tracción , Adolescente , Módulo de ElasticidadRESUMEN
BACKGROUND: Mechanical complications affect the stability of implant restorations and are a key concern for clinicians, especially with the frequent introduction of new implant designs featuring various structures and materials. This study evaluated the effect of different prosthetic index structure types and implant materials on the stress distribution of implant restorations using both in silico and in vitro methods. METHODS: Four finite element analysis (FEA) models of implant restorations were created, incorporating two prosthetic index structures (cross-fit (CF) and torc-fit (TF)) and two implant materials (titanium and titanium-zirconium). A static load was applied to each group. An in vitro study using digital image correlation (DIC) with a research scenario identical to that of the FEA was conducted for validation. The primary strain, sensitivity index, and equivalent von Mises stress were used to evaluate the outcomes. RESULTS: Changing the implant material from titanium to titanium-zirconium did not significantly affect the stress distribution or maximum stress value of other components, except for the implant itself. In the CF group, implants with a lower elastic modulus increased the stress on the screw. The TF group showed better stress distribution on the abutment and a lower stress value on the screw. The TF group demonstrated similar sensitivity for all components. DIC analysis revealed significant differences between TF-TiZr and CF-Ti in terms of the maximum (P < 0.001) and minimum principal strains (P < 0.05) on the implants and the minimum principal strains on the investment materials in both groups (P < 0.001). CONCLUSIONS: Changes in the implant material significantly affected the maximum stress of the implant. The TF group exhibited better structural integrity and reliability.
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Implantes Dentales , Materiales Dentales , Análisis del Estrés Dental , Análisis de Elementos Finitos , Titanio , Circonio , Circonio/química , Humanos , Materiales Dentales/química , Análisis del Estrés Dental/métodos , Estrés Mecánico , Diseño de Prótesis Dental , Módulo de Elasticidad , Simulación por Computador , Imagenología TridimensionalRESUMEN
Without intervention, cardiac arrhythmias pose a risk of fatality. However, timely intervention can be challenging in environments where transporting a large, heavy defibrillator is impractical, or emergency surgery to implant cardiac stimulation devices is not feasible. Here, we introduce an injectable cardiac stimulator, a syringe loaded with a nanoparticle solution comprising a conductive polymer and a monomer that, upon injection, forms a conductive structure around the heart for cardiac stimulation. Following treatment, the electrode is cleared from the body, eliminating the need for surgical extraction. The mixture adheres to the beating heart in vivo without disrupting its normal rhythm. The electrofunctionalized injectable cardiac stimulator demonstrates a tissue-compatible Young's modulus of 21 kPa and a high conductivity of 55 S/cm. The injected electrode facilitates electrocardiogram measurements, regulates heartbeat in vivo, and rectifies arrhythmia. Conductive functionality is maintained for five consecutive days, and no toxicity is observed at the organism, organ, or cellular levels.
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Arritmias Cardíacas , Animales , Arritmias Cardíacas/terapia , Arritmias Cardíacas/fisiopatología , Conductividad Eléctrica , Corazón/fisiología , Nanopartículas/química , Electrocardiografía , Humanos , Ratones , Frecuencia Cardíaca , Polímeros/química , Masculino , Inyecciones , Módulo de Elasticidad , Terapia por Estimulación Eléctrica/instrumentación , Terapia por Estimulación Eléctrica/métodos , Electrodos ImplantadosRESUMEN
Given the escalating environmental and safety concerns, friendly protective materials with exceptional mechanical properties, biodegradability, and insensitivity to high temperature have received more and more attention. Here, we report a robust cellulosic gel through the multi-scale integration of cellulose molecular skeleton, nano-reinforced diatomite, and in situ polymerized polyacrylamide molecule. The bottom-up yet cross-scale approach facilitates the formation of cellulosic gel characterized by a highly interconnected hydrogen bond network and nano-enhanced domain, resulting in a tensile strength of up to 13.83 MPa, a Young's modulus exceeding 280 MPa, and an impact strength around 12.38 KJ m-1. Furthermore, this gel exhibits structural stability at temperatures up to 130 °C, good flame retardancy, and complete biodegradability within a span of 35 days. The robust cellulosic gel, acting as a pliable protector, demonstrates exceptional protection for human joints. Our study presents a highly efficient and scalable pathway towards the development of sustainable and robust biomass gels, holding immense potential in intelligent-protective wearables and advanced materials science and engineering.
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Celulosa , Geles , Celulosa/química , Geles/química , Calor , Resistencia a la Tracción , Resinas Acrílicas/química , Enlace de Hidrógeno , Módulo de ElasticidadRESUMEN
Understanding the mechanical properties of porous carbon-based materials can lead to advancements in various applications, including energy storage, filtration, and lightweight structural components. Also, investigating how silicon doping affects these materials can help optimize their mechanical properties, potentially improving strength, durability, and other performance metrics. This research investigated the effects of atomic doping (Si particle up to 10 %) on the mechanical properties of the porous carbon matrix using molecular dynamics methods. Young's modulus, ultimate strength, radial distribution function, interaction energy, mean square displacement and potential energy of designed samples were reported. MD outputs predict the Si doping process improved the mechanical performance of porous structures. Numerically, Young's modulus of the C-based porous matrix increased from 234.33 GPa to 363.82 GPa by 5 % Si inserted into a pristine porous sample. Also, the ultimate strength increases from 48.54 to 115.93 GPa with increasing Si doping from 1 % to 5 %. Silicon doping enhances the bonding strength and reduces defects in the carbon matrix, leading to improved stiffness and load-bearing capacity. This results in significant increases in mechanical performance. However, excess Si may disrupt the optimal bonding network, leading to weaker connections within the matrix. Also, considering the negative value of potential energy in different doping percentages, it can be concluded that the amount of doping added up to 10 % does not disturb the initial structure and stability of the system, and the structure still has structural stability. So, we expected our introduced atomic samples to be used in actual applications.
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Carbono , Simulación de Dinámica Molecular , Silicio , Porosidad , Silicio/química , Carbono/química , Módulo de ElasticidadRESUMEN
BACKGROUND: Tissue engineering seeks to improve, maintain, or replace the biological functions of damaged organs or tissues with biological substitutes such as the development of scaffolds. In the case of bone tissue, they must have excellent mechanical properties like native bone. OBJECTIVE: In this work, three geometric models were designed for scaffolds with different structure lattices and porosity that could be biomechanically suitable and support cell growth for trabecular bone replacement applications in tissue engineering and regenerative medicine to the proximal femur area. METHODS: Geometries were designed using computer-aided design (CAD) software and evaluated using finite element analysis in compression tests. Three loads were considered according to the daily activity: 1177 N for slow walking, 2060 N for fast walking, and 245.25 N for a person in a bipedal position. All these loads for an adult weight of 75 kg. For each of them, three biomaterials were assigned: two polymers (poly-glycolic acid (PGA) and poly-lactic acid (PLA)) and one mineral (hydroxyapatite (HA)). 54 tests were performed: 27 for each of the tests. RESULTS: The results showed Young's modulus (E) between 1 and 4 GPa. CONCLUSION: If the resultant E is in the range of 0.1 to 5 GPa, the biomaterial is considered an appropriate alternative for the trabecular bone which is the main component of the proximal bone. However, for the models applied in this study, the best option is the poly-lactic acid which will allow absorbing the acting loads.
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Diseño Asistido por Computadora , Análisis de Elementos Finitos , Ingeniería de Tejidos , Andamios del Tejido , Andamios del Tejido/química , Humanos , Ingeniería de Tejidos/métodos , Durapatita/química , Módulo de Elasticidad , Bioimpresión/métodos , Poliésteres/química , Porosidad , Simulación por Computador , Materiales Biocompatibles/química , Sustitutos de Huesos/química , Ácido Poliglicólico/química , Impresión Tridimensional , Ensayo de Materiales , HuesosRESUMEN
In this paper, the geometric analysis of carbon nanotubes (CNTs) without external loading is carried out by energy method. Based on the theory of molecular mechanics, an improved mechanical model is proposed to predict the energy of armchair carbon nanotubes under stress-free conditions, and the diameter of CNTs is estimated according to the principle of minimum energy. The results show that the diameter obtained by the improved model is larger, but basically consistent with that obtained by conformal mapping. The inversion energy term is added to the modified model, and the inversion energy term related to atomic curvature is characterized by the conization angle. It can be seen from the error that the inversion energy of carbon nanotubes can not be neglected in the stress-free state, especially in the case of small diameter. The agglomeration of nanotubes is one of the important factors, which affects the effective elastic modulus of nanocomposites. Here, a new micro-mechanics model consisting of both agglomeration of CNTs and pure matrix is also presented to analyze its effect on the effective elastic modulus. It is noted from the results that the stiffness of nanocomposites is very sensitive to the CNTs agglomeration.
Asunto(s)
Nanocompuestos , Nanotubos de Carbono , Polímeros , Nanotubos de Carbono/química , Polímeros/química , Nanocompuestos/química , Módulo de Elasticidad , Modelos Moleculares , TermodinámicaRESUMEN
Dentin is a biological composite exhibiting multilevel hierarchical structure, which confers excellent damage tolerance to this tissue. Despite the progress in characterization of fracture behavior of dentin, the contribution of composite structure consisting of peritubular dentin (PTD), intertubular dentin (ITD) and tubules to fracture resistance remains elusive. In this study, calculations are carried out for energy release rate associated with crack propagation in the microstructure of dentin. Crack penetration and deflection at the PTD-ITD interface are accounted for in the numerical analyses. It is found that high stiffness of the PTD plays a role in increasing crack driving force, promoting crack growth in the microstructure of dentin. For crack penetration across the PTD-ITD interface, the crack driving force increases with increasing tubule radius; and thick PTD generates amplified crack driving force, thereby leading to weak fracture resistance. The driving force for crack deflection increases with the increase in tubule radius in the case of short cracks, while for long cracks, there is a decrease in driving force with increasing tubule radius. Furthermore, we show that the competition between crack penetration and deflection at the PTD-ITD interface is controlled by the ratio of PTD to ITD elastic modulus, tubule radius and thickness of PTD. High PTD stiffness can increase the propensity of crack deflection. The microstructure of dentin with large tubule radius favors crack deflection and thick PTD is beneficial for crack penetration.